CHAPTER 7 - WWII JAPANESE MILITARY TACTICS - SECTION 5



TABLE OF CONTENTS








CHAPTER VII - TACTICS OF THE JAPANSES ARMY.


INTRODUCTION.
The basic tactical principles of the Japanese Army have been carefully developed from studies of foreign army techniques and its own valuable experiences gained in combat under varying conditions. Japanese forces have fought against regular military organizations of several first-class nations and have had considerable experience in combating the constant harassing action of guerrillas on supply lines and rear areas.

They have engaged in tank actions on the plains of Manchuria and in mountain battles in Central and Southern China; they have conducted landing operations under varying conditions of terrain and climate. They have been highly successful in their earlier jungle operations, on terrain where good roads and railroads are practically unknown, and where every type of natural obstacle exists. They are not merely jungle fighters, however, for much of their success has been on terrain where principles of open warfare have been applied effectively. By studying the areas over which they expected to operate they effectively organized, trained, and equipped their forces and evolved techniques designed in each case to fit the terrain and meet the logistical requirements peculiar to their own army.

The Japanese lay great stress on offensive actions, surprise, and rapidity of movement, with all commanders and staffs operating well forward in order to keep themselves constantly informed of the situation. Their tactical doctrine is based on the principle that a simple plan, carried through with power and determination, coupled with speed of maneuver, will so disrupt the plan. of hostile forces that success will ensue. Combat orders, in both attack and defense, from the highest to the lowest unit, generally carry the admonition that the "enemy forces will be annihilated." Surprise is an ever present element, while the envelopment is the preferred form of attack.



Thorough reconnaissance also is taught, and the practice of infiltration is greatly stressed. The Japanese willingness to attack a position with forces which other nations would consider insufficient for the task, is based on the assumption of their so-called military superiority. An explanation of this assumption calls for an analysis of Japanese psychology, national vanity, and past military successes, which is beyond the scope of this study. To the Japanese officer, considerations of "face" and "toughness" are most important, and they are therefore prone to indulgence in "paper" heroics. They have evinGed boldness against poorly equipped troops; however, against first-class, wellequipped forces, it may be expected that they will adopt more circumspect methods.

Despite the opportunities presented during 6 years of active combat, the Japanese have continued to violate certain fundamental principles of accepted tactics and technique. Their tendency to persist in such violations is based primarily upon their failure to credit the enemy with good judgment and equal military efficiency. Whether or not they have profited by recent experiences remains to be seen.


SECTION I. GENERAL.
The part on the General Tactical Doctrine of the Japanese Army is based on actual observation of their field maneuvers, and map problems their. operations against Russia and China and a study of their field manuals. It is believed that theiT tactical principles, taught and studied for years, will nol change ma tetra II y. The tactical methods described here are primarily those which the Japanese consider appropriate for fighting in open country such as North Asia. They have had ample opportunity to test their tactics and to observe those employed by other Armies.

Any study of their teachings must be approached with the knowledge that the Japanese are quick to copy and may even improve on the tactics of their enemies. Technique, or application of tactical principles, will vary, and is limited only by the imagination and initiative of individual commanders.




DOCTRINE.
Japanese tactical doctrine insists vigorously on the inherent superiority of the offense, and Field Service Regulations state that the offensive should be resolutely taken. The object of all maneuver is to close quickly with the enemy so that the assumed Japanese superiority in close combat can be realized to the utmost. Even when the enemy strength is markedly superior, or when the Japanese commander has been placed temporarily on the defensive, he is supposed to use every effort to regain the offensive and take the initiative.

The Japanese seem to feel that there is some mystic virtue in the attack and defensive combat is looked upon as a negative form of action to be adopted only when confronted with a markedly superior enemy. Even in defense, the offensive principle is strongly emphasized. Both as a result of this training and because of faith in the offensive doctrine, Japanese officers often reach attack decisions where, by all orthodox tactics, the situation patently requires some form of defensive action.

Their teachings have been found to place very little emphasis on time and space factors, with the result that concentration of effort and the cooperation of all arms are frequently neglected. The division used for illustrative purposes in this section is the Japanese triangular division. It should be borne in mind, however, that while all Japanese divisions are not identically organized, tactics will not materially differ, although there will be differences in composition of columns and grouping of units.


FORMS OF ATTACK.

a. Envelopment.

(1) The Japanese consider the envelopment as the preferred offensive maneuver. Envelopment will be· accompanied by a determined frontal pressure, while the main force attacks a flank. In ascending order of effectiveness, the envelopment may be single, double, or a complete encirclement ( kanzen hoi ). Contrary to generally accepted tactical prbciples, the Japanese are willing to try a double envelopment without any considerable numerical superiority and regard it as possible, sometimes, even by an inferior force which relies on surprise and deception. The Japanese commander may seek to obtain envelopment in one of several ways.

(a) The force advances in two or more parallel columns, with one or more columns directed toward the enemy flank and rear during the advance to contact.

(b) The force advances with certain units in the rear which can later be deployed to execute a flank envelopment.

(c) After the force has encountered the enemy and partially deployed, some units may be moved laterally for envelopment if natural cover, darkness, fog, or ·smoke are available.

(2) The procedure of (1)(a) above is considered the normal one for units of the size of a division; (1)(b) is especially applicable to small units, but (1)(c) is considered feasible only under most favorable conditions. Those units of a division executing the frontal holding attack often will make a close-in envelopment in performing their mission. Units of this force, such as squads and platoons, seek to obtain the effect of flanking fire ( shageki hoi ).

(3) The question of which flank to envelop is decided by weighing normal factors such as terrain, location of hostile reserves and heavy weapons, etc.

(4) To increase the effectiveness of the envelopment the Japanese often send a small force around to attack the enemy rear. When such a movement ( ukai ) is employed, the force sent around by a division in attack is relatively weak, comprising about a battalion reinforced by light artillery and a squad of engineers. The mission of such a turning force is often similar to that of a pursuit detachment; in fact this force may become a pursuit detachment if the main attack succeeds.

b. Frontal attack.

(1) Japanese regulations contain the usual admonitions against a frontal attack. Situations which may give rise to a frontal attack are those to which Allied armies are accustomed. In observed practice, however, the time eiement, or the fear of allowing the enemy leisure to improve his position, often is allowed to justify a questionable decision to make a frontat attack.

(2) The main effort of a frontal attack is made against a "soft spot" in the line, leading in a decisive direction into the enemy rear areas. Effort will be made to penetrate deeply and swiftly at the first attempt by keeping narrow the battle fronts of units in the area of the main attack. making dispositions in depth and coordinating employment of artillery. Tanks, if available, may participate In general, the Japanese are weak in artillery support and depend heavily 11 extensive employment of their infantiy guns and infiltration practices.

c. Comments.

The impressions gained from a study of Japanese teachings on the forms of attack and their application in practice show that:

(1) The Japanese will attack in many cases where the orthodox decision would call for less positive action. The attack may be rash and costly but will never lack vigor and detennmation.

(2) The frontal attack, often with inadequate supporting arms, is not uncommon.




MEETING ENGAGEMENT (ENCOUNTER).

a. Doctrine. The meeting engagemeut is the foundation of Japanese combat training with official regulations giving more spaue to it than to any other form of combat. Japanese military writings define the meeting engagement as the collision of two hostile forces in motion, or the meeting of a force in motion with one which has halted but has not had time to organize a detailed position. Training strongly emphasizes this form of combat as allowing the optimum development of the alleged Japanese aptitude for swift and decisive offensive action.

b. Artillery seems to be assigned missions in excess of its capabilities. Aircraft are expected to conduct constant reconnaissance of the situation of enemy and friendly troops as well as to cooperate with the artillery. Tanks may be used independently or in direct support of the infantry; when they are sent on distant raids, other mobile units, if available, may accompany them.

c. The rules governing the Japanese in the meeting engagement may be summarized as follows:

(1) The seizure and retention of the initiative.
(2) Bold, independent action by subordinate commanders.
(3) Prompt occupation of important terrain features.
(4) Energetic leadership during combat.

d. In the words of a Japanese writer, "The Imperial Army seeks to wage a short war to a quick and decisive conclusion. The meeting engagement conforms to this spirit and is to be sought whenever possible."


ADVANCE.

a. General.

The formations in the advance in day or night movements are similar to those used by other Armies and are governed by the same considerations. Parallel columns, each self-contained, are usual, unless precluded by the road net. When the enemy is strong in aviation and mechanized units, long columns are broken up into short serials containing antiaircraft and antitank weapons.

Each main column is preceded by an advance guard, while the division cavalry, if present, usually acts as a reconnaissance screen in front of the advance guards. When the division is to advance at night, the division commander often sends forward in daylight a reconnaissance detachment and motorized infantry to seize important terrain features and to cover the night movement.

As a meeting engagement becomes likely, the division commander modifies the formation, as needed, to facilitate the entry of the division into action with a view to enveloping one or both flanks of the enemy.

b. Advance in two columns.

(1) A study of Japanese tactical problems illustrates the division advancing in one, two, and three columns, with the two-column formation being the most favored. In the two-column formation the essential components of the division are disposed as follows:


Reconnaissance Detachment


1st Cavalry


(Less detachment)




Left Column Right Column
Advance guard
1st Infantry Regiment (less 3d Battalion)
1st Company 1st Ind Antitank battalion
1st Battalion 1st FA Regiment
1st Company 1st Engineer Regiment
1/3 Decontamination Unit
1/3 Casualty Clearing Unit
2nd Infantry Regiment (less 3rd Battalion)
2nd Company 1st Ind Antitank Battalion
2nd Battalion 1st FA Regiment
1st Engineers (less 1st company)
1/3 Decontamination Unit
1/3 Casualty Clearing Unit
Main Body
Division headquarters
Infantry Group Headquarters
1st Troop (Company) 1st Cavalry Regiment
3rd Battalion 2nd Infantry Regiment
1st FA Regiment (less 1st and 2nd Battalions)
1st Ind Antitank Battalion (less 1st and 2nd Companies)
1st Battalion 1st Medical FA Regiment (150-mm Howitzer)
3rd Infantry Regiment
3rd Battalion 1st Infantry regiment
Advance Section, 1st Transport Regiment
Diviison trains
1st Transport Regiment (less detachment)
1/3 Decontamination Unit
1/2 Casualty Clearing Unit

With the above formation, the division commander expects, if anticipatory plans have been correct, to execute an envelopment of the hostile left flank.
Figure 80.

(2) The composition of the march column illustrated above is covered in the division field order. It is noteworthy that an advance guard is designated by the division commander for the right column only; the left column merely receives an indication of the units composing it. This march formation is the result of the curious system of command which the Japanese employ. The division commander concurrently commands the division and the right column. In the latter capacity, he prescribes the detailed organization of the right column. The detailed organization of the left column falls to the senior commander of that column who designates an advance guard for its protection. Thus the advance guard of the left column is not an instrumentality for the protection of the division as a whole and is not directly under the control of the division commander. Therefore, as a meeting engagement becomes imminent, the immediate subordinates to whom the division commander issues orders directly are the colonel of the 1st Cavalry Regiment (commanding the reconnaissance detachment), advance guard commander (right column), commanders of the major components of the right column, and the commander of the left column. It is not clear how the division commander plans to coordinate the action of his right column advance guard with that of the left column. The term "advance guard" as subsequently used applies only to that which is controlled directly by the division commander.

(3) In the above formation,, the infantry strength in the advance guards of the 2 columns is about one-third of the division's infantry. When there is a greater number of columns employed, the combined infantry strength of the advance guards sometimes reaches half that of the division. Strong advance guards are characteristic of the Japanese Army in approaching a meeting engagement.

c. Advance in other than two columns.

An advance in one column is avoided because of the delay incident to developing the division for an attack. Therefore whenever that formation is adopted it is imposed by limitations of the road net. An advance in 3 columns was undertaken by a Japanese infantry division at Rangoon in March 1942, as follows:

LEFT CENTER RIGHT
One Battalion Infantry (less one Company)

One Company Engineers (less one PI) with collapsible boats.
One Infantry Regiment (less one Battalion - Less one Company)

One Company FA (pack) with Ind Tpt Unit.

One Company Engineers (less one PI)

One Ind A/Tk Company (37-mm)

Detch Division Medical Unit

Detch water purification unit

One company Ind Tpt Unit

One section Division Signal Unit
Infantry Regiment

One Battalion FA (Pack) (less one company)

Tpt Unit (less detachment)

One PI Engineer Division Medical Unit (less detachment)

Water purification unit (less detachment)

One Company Army Signal Troops.

Two Sections Division Signal Unit.

Figure 81.

The whereabouts of the remainder of the division is not known. The above illustration is taken from a British source which states that the initial advance of the division was made by 2 regiments, i. e., 6 battalions, spread over a frontage of 40 miles. The 3 columns were divided. with approximately a 20- mile space between each. In this case the left column hardly could be considered as self contained. Use was made of roads, trails, and waterways wherever possible. In advance in 3 columns, the division commander remains the commander of the strongest column. More than 3 columns may be found, but such employment will be exceptional.

d. Transport and trains.

The division transport and trains normally follow the main columns of the division under division control in the following order: advance section transport regiment, unit trains, and the remainder of the transport regiment. Distances between these units are normally from 1 to 2.5 miles. The massed trains are under a commander, who is designated by the division commander. The advance section of the transport regiment consists of an infantry ammunition section, 2 artillery ammunition sections, and a veterinary section. Two field hospitals may be attached to the advance section of the transport regiment.



e. Attachments.

Units of light and medium artillery, antiaircraft artillery, observation aviation, antitank units and other supports frequently are attached to a division in the advance.

f. Antiaircraft protection on march.

For the advance, each front-line division may have attached an antiaircraft organization. This unit, often motorized, moves by leapfrogging from critical point to critical point along the axis of the division's advance. The guns go into position during the noonday halt, while passing defiles, while in bivouac, etc. If possible, antiaircraft units move forward by roads not used by the other elements of the division. The effective radius of action of one company of 75-mm antiaircraft artillery is considered to be 6,800 yards.

g. Antitank protection on the march.

In areas where there is a threat of enemy tank action against a column, the Japanese usually hold some tanks in readiness for employment against hostile tank forces. Active reconnaissance by both air and cavalry units warns the division commander of impending hostile tank action. Antiaircraft artillery may at times be employed to supplement normal antitank protection measures.

h. Advance detachments,

(1) There is a notable tendency for the division commander to send forward a mobile detachment in advance of the division for one of the following purposes:

(a) To cover a night march to the probable battlefield where the division expects to be committed to action shortly after daylight.

(b) To secure a vital terrain feature on the front of the division.

(c) To execute demolitions of the road net and hamper the movement of the enemy.

(d) To execute surprise attacks while the enemy is in march formation.

(2) These detachments generally consist of the division cavalry, some infantry and engineers in trucks, and a company of light artillery. The infantry strength ordinarily will not exceed a regiment, except where the division plans an active defense. In this latter case, as much aS half of the division may be pushed forward by forced marches to occupy a defensive position, while the remainder of the division follows more slowly with the intention of launching a counteroffensive against an enemy flank.


ACTIONS OF THE DIVISION COMMANDER IN APPROACHING A MEETING ENGAGEMENT.

a. Reconnaissance.
The formation of the advancing division contains in it the germ of the maneuver which the division commander expects to adopt if he encounters the enemy on the march, When the hostile force is reported approaching from a considerable distance, the division commander estimates where the battle will occur and communicates to his subordinates the general plan of maneuver which he expects to adopt, taking into consideration the use of terrain which the enemy considers generally impassable. He indicates time and place for the delivery of reports and designates a message dropping ground for the air service. His artille1y and engineer commanders receive technical informaion from their own patrols marching with the advance guard and reconnaissance detachment. As contact becomes imminent the division commander, hithereto marching at the head of the main body of the principal column, moves forward on personal reconnaissance accompanied by appropriate staff officers. An advance message center may be designated behind the advance guard, one of the important functions of which is to facilitate collection and dissemination of enemy information.

b. Orders.
From his personal reconnaissance and the reports of his reconnaissance agencies, the division cmmander determines the area in which the division will make its decisive effort, the plan of maneuver, and the location of the division command post. He then issues fragmentary operational orders to initiate deployment of the division. Japanese Combat Regulations warn against waiting for overdetailed information before reaching a decision, and this injunction seems to authorize a very short reconnaissance phase at this point.






DEPLOYMENT OF DIVISION.

a. Advance guard.

(1) (a) The advance guard in the meeti~g engagement performs the following functions: it secures enemy and terrain information needed to form the basis of the decision of the division commander; it protects the deployment of the main body; and secures important terrain features to facilitate the subsequent attack.

(b) The advance guard commander, bearing in mind these general functions, is expected to exercise initiative and boldness of action in specific cases. He obtains the necessary information by vigorous patrolling and, if necessary, by a small-scale attack. He protects the deployment of the division, either by offensive or defensive methods, and attacks when necessary to obtain important geographical points. Left to his own devices, however, the advance-guard commander usually elects to drive headlong into the advancing enemy, unless specifically restrained by division order.

(2) As the advance guard closes to contact, its artillery prepares to furnish continuous support by leapfrogging from position to position in rear of the infantry. Normal artillery missions are to interdict (harass) the movement of enemy columns, to support the action of the advance guard infantry, and to perform limited counter-battery missions. Extreme ranges for interdiction by the 75's are 7,500 to 9,000 yards, but in practice missions are seldom fired at over 5,500 yards. Positions are chosen with a view to supporting the attack of the main body without change of position. The advance- guard artillery reverts to the control of the artillery commander at the time of the attack of the main body.

(3) It must be borne in mind that the advance guard discussed is that of the column directly commanded by the division commander. The security detachments in advance of other columns are for their local protection only.

b. Main body,

(1) Deployment.

(a) In his basic decision for the deployment of his division, the division commander determines whether it will be coordinated or piecemeal. The basis for this decision is found in the Japanese Combat Regulations, a translation of which reads: "The division commander, in order to profit by or to extend an advantage won by the advance guard, may have to commit to combat each march column and each element of the main body successively upon arrival. However, if the situation permits, the division commander should seek the coordinated entry into action of his units, in which case he orders the deployment of each unit, establishes close cooperation between infantry and artillery, and coordinates the time of the infantry attack."

(b) The question of whether to make a piecemeal attack thus appears to be decided largely by the success of the advance guard action. In map problems studied, the piecemeal engagement of all or part of a force often is justified by the necessity of seizing some prominent terrain feature or by the desire to get out of a defile. The object of the piecemeal attack is to take advantage of a sudden opportunity, while the coordinated attack aims at securing effective use of the combined arms at the expense of time.

(2) Coordinated deployment.

(a) As indicated above, the Japanese prefer a coordinated development "if the situation permits." The measures taken by the division commander to secure this coordination are: the assignment of a line of departure (tenkaisen) behind which the major units of his command are to deploy for the attack; detailed arrangements to assure coordination between the artillery and the infantry; and announcement of an hour of crossing the line of departure. The line of departure is usually an extension of the line held by the advance guard. If the enemy has secured the advantage of priority in deployment, the main body of the division may endeavor to escape a threatened envelopment or premature engagement with superior numbers by deployment along a line behinll the advance guard or to the flank and rear thereof. In the event the deployment is to the flank and rear, the advance guard supported by all the division artillery covers the deployment and delays the advance of the enemy.

(b) If the enemy, in anticipation of a collision with the Japanese troops, assumes the defensive, the deployment is modified to resemble the relatively cautious procedure of the attack of a position. In this case also the division commander tries to develop and attack in the same day to avoid giving the enemy time to improve his position.

(c) The phase of the passage from march column to complete deployment is indicated by the following nomenclature used in Japanese regulations: (It must be realized that the following definitions are the translation of the Japanese and do not necessarily bear the same connotations in the Allied terminology.)

1. Bunshin. Breaking from march column into small ones out of hostile artillery range at the beginning of the approach march.

2. Tenkai. Deployment along a line of departure (tenkaisen) with a view to performing an assigned combat mission.

3. Sakai. Advance from the tenkaisen in small (squad or section) columns.

4. Sankai. Final deployment of front-line units to permit firing during the last few hundred yards of the assault.

These phases are shown diagrammatically in figure 82.


Figure 82. Route column.

(d) It is important to note that the coordinated attack from the Japanese point of view does not imply passing into assembly areas. However, this passage into assembly areas, called "kaishin" usually is observed in the attack of a position. If a coordinated attack follows the meeting engagement, columns deploy directly behind the line of departure (tenkaisen) without halting prior to arriving on it. No special time is allotted for ammunition issue and final reconnaissance.

(3) Piecemeal attack.

(a) In the piecemeal attack the troops are committed to action in order of their arrival on the field. The division commander, decentralizing control to his column commanders, limits himself to a designation of routes of advance with a view· to subsequent attack in the desired directions. No division "tenkaisen," no common hour of attack, and no detailed plans for coordination between the various arms are stipulated.

(b) Despite the lip service rendered in regulations to the coordinated deployment and attack, the piecemeal method is very common on the map on the maneuver ground, and in observed operations. Often this is the result of the precipitate action of the advance guard commander who gets himself seriously engaged on his own initiative. In such a case, a Sort of hybrid deployment sometimes is executed. vith a part of the main body going in piecemeal to help the advance guard, while the remainder makes an orderly deploymeut. Occasionally, a column commander has been known to stage a piecemeal attack all of his own in a situation where the prompt seizure of a terrain feature on his front seemed essential to the subsequent success of the division. Such action was taken without waiting for orders or authorization from the division commander.

(c) The rate of march of the infantry as it enters the zone of effective hostile artillery fire is reduced. In this zone the artiller moves forward by bounds of battalion. while furnishing continuous support to the infantry. The theoratical rate of movement forward for this artillery is 2.5 miles per hour, although this may be increased to about 5 miles per hour if a battalion is allotted a road for its exclusive use. As the range limit is reached the battalion prepares to move forward.



(d) Unit trains.

When contact becomes imminent the transport regiment and the unit trains are halted in a sheltered location. The advance section of the transport regiment will often be as close as 2.5 miles to the anticipated contact, while the trains are normally about 5 to 6 miles in the rear of this line. The remainder of the transport regiment will be behind the trains.


DIVISION ATTACK ORDER.

a. Deployment.

The division deployment order gives a combat mission to the advance guard and march directions to the several columns with a view to executing a preconceived maneuver. While the elements of his command are carrrying out these orders, the division commander watches the development of the advance-guard action and, with a minimum of delay, issues a verbal attack order to his principal subordinates.

b. Attack order.

The division attack order generally is issued in fragmentary form to the commanders concerned.

c. Orders to infantry.

In the organization of the infantry for combat, the advance-guard infantry becomes one wing and executes the holding attack. The second regiment executes the main attack and it may deploy as the other wing along a line of depmtuTe ( tenkuisen) . generally in prolongation of the ad½nce guard position. About one regiment of infantry is held in division reserve. This attack order is issued when the enemy is fixed in a given area where contact is expected, but often prior to making actual contact and before the advance guard has developed the situation. The order assigns to the infantry wing(s) specific objectives or a very general attack mission, depending upon the degree of clarity of tbe situation. Specific objectives would be such as "to attack the hostile forces on X ridge and seize the X position," while a general attack mi55ion might be something like "to advance in the direction of Y and locate and attack the enemy's right flank." This latter type of objective is appropriate in an obscure situation when the plan of maneuver is predicated largely on a study of the terrain. In this case the attack direction given is one which is certain to take in flank any formation or position which the enemy may reasonably assume. A study of Japane attack orders reveals that in an extreme case an order was issued 7.4 miles from the expected point of contact of the advance guards.

d. Orders to artillery.

(1) The artillery order indicates the localion of the positions in general terms. and detailed reconnaissance is made by artillery commanders to determine the exact locations. Attachment of artillery to infantry is considered to be justified when:

(a) The front of attack is very wide.
(b) Liaisoa with the infantry is difficult.
(c) Combat begins unexpectedly.
(d) The terrain is brokeu and wooded.

(2) In the normal case the division retains control of the artillery and coordinates its action. Typical mission during the successive phases of the combat are as follow :

(a) Phase I.
During the approach march and deployment.

1. Objectives (targets)
in order of importance. Hostile artillery and machine guns firing at extreme ranges.

2. Purpose.
To cover the deployment of the infantry.

(b) Phase II. During the attack.

1. Objectives (targets)
in order of importance. Hostile infantry, artillery, and reserves.

2. Purpose.
Close support of infantry.

(c) Phase III.
During final assault.

1. Objectives (targets) in order of importance. The area of the decisive attack; the enemy reserves.

2. Purpose. Neutralization and interdiction (harassing) of movement of reinforcements.

e. Orders for piecemeal attack.

The division attack order described in the foregoing applies to the coordinated attack. In the piecemeal engagement columns are organized into wings and receive attack directions and the attachment o{ the proper auxiliary arms. There is no coordinated deployment of any unit larger than a battalion. The artillery, less detachmeuts, is kept under division control. The maneuver takes the form of a frontal collision without any effort to coordinate direction of the various columns to obtain the effect of envelopment.




FRONTAGES AND DISTANCES.

a. Frontages.

The following frontages are averages derived from studies of several problems:

Battalion as a covering force 1,600 yards
Regiment in a holding attack 3,000 to 4,400 yards
Regiment in the decisive attack 1,600 to 2,200 yards


b. Distances.

Distances from the line of departure.

Division command post 2,200 to 3,300 yards
Artillery positions 600 to 1,500 yards
Division reserve 1,200 to 2,800 yards
Advance echelon, division transport 4,500 to 6,500 yards
Unit trains 8,800 to 11,000 yards
Remainder of division transport 11,000 to 13,000


c. Assault.

Attacking units do not try to retain alignment, and where the going is easy they press ahead. When gassed arnas may be encouutered the leading wave includes decontamination squads. A gassed area is avoided when p0ssible; if it must be traversed the local gas squads use their light decontaminatlng equipment to neutralize it.

When such equipment is insuflicient or absent, the troops are taught to cross the gassed area resolutely at an increased gait. The artillery advance by bounds close behind the infantry, while its forward ohserver adVance with the inlantry. As the attacking infantry approach the enemy position , infantry and artillery fire is increased, and reserve units are broughL up.

The cavalry closes in on the enemy flank and rear, and victOry is won by closing with the bayonet. The division reserVe is used to extend and exploit an advantage gained, to meet a couterattack, or to extend the flank of the enveloping forces. If darkness interrupts the altack, it will be continued at night Or renewed at dawn.




COMMENTS.

a. Meeting engagement.

In the Japanese meeting engagement all elements of the division show boldness and vigor. Speed in decision and execution is stressed in regulations and carried out in application. A commander encountering a Japanese division may expect to receive a quick and energetic attack, and, unless his covering forces are solidly deployed on their position, the Japanese attack is likely to upseL his own plans for a coordinated attaok.

b. Piecemeal action.

In practice the Japanese have shown an excessive willingness Lo engage in piecemeal action; Allied combat rergulations. on the other hand, strongly favor the coordinated attack. Generally, according to Allied doctrine, the piecemeal attack is considered justifiable only if time is pressing, if there is a limited objective, and if comat superiority is on the attacker's side. If these cTiteria are applied to the situations in which the Japanese commander has decided to make a piecemeal attack, it will be found that time is presing, and there is usually a limited objective, hut not necessarily superiority. In fact, in the problems studied, the enemy was always superior, and in at least an equal state of readiness for combat. (In one map problem, the Japanese division was marching in one column while the enemy was in two) . The only combat superiority was in the mind of the Japanese commander. Such a doctrine tends to make wasteful, piecemeal action the rule rather than the exception and develops a dangerous over-confidence, unjustified when faced by first-class troops.

c. March formation.

The march formation in which the division commander is also a column commander is awkward, for it needlessly burdens the division commander with the details of organizing and commanding a column. It complicates the handling of the advance guar ds which are usually not coordinated under div ision control. In fact, the advance guards of columns adjacent to the one commanded by the division commander generally are ignored in the division plan of maneuver. As a result the division does not appear to develop behind solidly organized covering forces which can assure an uninterrupted deployment through coordinated defensive action, even though the numerical infantry strength of the advance guards is usually large, averaging from a third to a half of the infantry of the division.

d. Faults.

The frequent use of the advance guard reinforced to make a holding attack and generally deployed on a wide front, renders control difficult and the organization of an effective attack even more difficult. The close-in envelopment so often chosen arises from a desire to get the attack off quickly and from the weakness of the organic artillery of the division. The Japanese teachings are to keep the artillery in a central location so that fire can be maneuv ered over most of the front of both holding and enveloping attacks. If done this would restrict the scope of the possible attack directions.

e. Reconnaissance.

Map problems and terrain exercises which have been studied show that an insufficient time is allocated for reconnaissance and organization of the attack. In one map problem only 1 ½ hours elapsed between the decision of the division commander and the jump-off of the so-called coordinated attack. While this is an extreme case, the impression of insufficiency of time for preparation is general.

f. Summary

In summary, the characteristics of the Japanese division in the meeting engagement are:

(1) Rapid, aggressive offensive action by all elements.
(2) A tendency to uncoordinated piecemeal action.
(3) Development behind weakly linked covering forces.
(4) I Frontal attack or restricted close-in envelopments.
(5) Inadequate artillery support.
(6) Sacrifice of proper reconnaissance and organization to obtain speed in attack.
(7) Attack through terrain generally considered to be impossible,




ATTACK OF POSITION.

a. General.
When the enemy has had time to occupy and Organize a position, the Japanese commander endeavors to fight the decisive action outside of the organized area by turning the position. This is often attempted by an approach over terrain said to be impassible or under adverse weather conditions. The intention in both cases is to achieve sUrprise in the direction and time of attack. However, the presence of other Japauese units on the flanks often may limit the possible maneuver area. The technique of such an attack resembles that of the coordinated meeting engagement in the use of the approach march and the development of the situation by the advance elements; il differs in the amount of time necessary for reconnaisance and attack preparations. However, the need for carefully executed attack preparations, according to the Japanese, must not be made the excuse for allowing the enemy undue time to improve his position . As shown in map problems, when a commander encounters a position which has been strengthened during a period of several days, he ordinarily drives in the covering forces and reconnoiters during all or part of one day and launches his main attack the following morning. He appears quite capable of attempting all of this in one day if time is pressing.


b. Development.
(1) The hostile position normally will be covered by outposts which will vary in strength from patrols to a relatively strong force supported by artillery and deployed as an outpost line of resistance. As the Japanese advance guards approach contact with the covering force, and before the main body comes under long-range artillery fire, the division commander usually orders his column into assembly areas.

(2) It should be noted that going into assembly areas is a phase of the attack of a position not ordinarily present in the meeting engagement. In problems studied these areas are from 2,200 to 4,400 yards from a hostile outpost line and thus 4,000 to 6,000 yaTd from the hostile artillery. In the typical case of the division advancing in two columns three assembly areas are designated, one for the main attack force, one for the force making the secondary effort, and one for the division reserve. The assembly is covered from positions about 1,100 to 1,600 yards in advance.


DRIVING IN COVERING FORCES.

a. Procedure.
In order to obtain adequate information about the main defensive position, the Japanese division ordinarily first drives in the hostile covering forces and then executes the necessary reconnaissance for the main attack. If these covering forces are weak and do not form a continuous front, the advance guard commander drives them in on his own intiative; otherwise, the division commander organizes the operation under cover of strong artillery support. In the typical case, this attack takes place in the afternoon of one day, and is followed by attack of the main position at daylight the next day or shortly thereafter. When the Opposing forces occupy positions very close together, two nights may be necessary to get the attacking forces and materiel into position.

b. Continuous attack
This procedure of successive attacks, while designated as orthodox in Japanese Combat Regulations, often is replaced in pratice by a continuous attack on both outpost and main position. It is not clear when this variation is considered justified but apparently the deciding factors are whether the aTtillery can suppott the attack through both positions without displacement (moving) and whether the time element is pressing.

When the continuous attack is made, that on the outpost line becomes a phase of the main attack, and the attacking infantry usually pauses briefly on the captured position, and then continues the assault. In about half of the map problems studied the continuous method was adopted, although there was no apparent need for especial haste in launching the attack.


ATTACK ORDER.

While the infantry is deploying in assembly area (kaishin haichi) and the advance guard is driving the covering force the divislon commander after completion of hls plan of attack based on reconnaissance reports, issues his order for the final deployment of the division and the subsequent attack. The order includes familiar elements, except that the infantry in the assault is divided into right and left wings (occassionally into a right wing left wing, and center) in accordance with the scheme of maneuver.


TECHNIQUE OF ATTACK.

a. Infantry.
(1) The typical disposition oi the units in the assault is into wings, with the preponderance of strength in one wing assigned to make the main effort, while th other wing makes the secondary attack. The infantry units, in accordance with the plan of deployment advance from the assembly areas to their assigned position along the line of departure where they make final attack preparations.

Wben the attack is to jump-off about dawn (first light, the advance to the line of depaTture is made under cover of darkness; if made in daylight all means are utilized to conceal and protect this movement. In problems, the lines of departure vary from 550 to 2,000 yards from the enemy main position, and the line is chosen so as to be protected from effective small-arms fire. When the attack on the main line of resistance and the outpost line of resistance is continuous, a pause and a realignment may take place along the rear edge of the outpost position which then becomes a phase line in the course of the attack. Attack objectives (terrain features) or attack directions are given the frontline infantry units according to the known details of the enemy position. Normally, the line to be reached by the attack is deep in the zone of the hostile artillery.

The hour of attack is usually about 1 or 2 hours after dawn, as the Japanese have little confidence in the ability of their artillery to adjust and fire a preparation at night. In case of an attack entirely in daylight, a minimum of 4 hours is allowed between the time of the attack order and the assault to provide for distribution of the order and for artillery prnparation.

(2) In the decicive effort the average frontages of attack are:

 
1 Company 225 yards
2 Battalion 400 to 600 yards
3 Regiment 1,100 yards
 


Frontage are 20 to 25 per cent greater for units making the secondary attack.

(3) The division reserve is assembled under cover in the zone of the main effort approximately l½ to 2 mile Irom the line of departure.

b. Tank.

When available, tanks are brought up with great secrecy to assault positions. Here they are attached to front-line battalions and jump off at the same time as the front-line infantry. The infantry is warned not to stop if the tanks are destroyed but to continue the advance. Tank missions are the breaching of enemy wire and destruction or neutralization of hostile elements.

c. Artillery.

(1) The division artillery frequently is reinforced with light and medium battalions. Its combat organization usually provides for a direct support group of from one to two battalions for each wing without any artillery being held in general support. If a fourth battalion is attached it may be employed as a counter-battery group in a relation similar to general support. Fire missions are varied according to the phases of the proposed action, a typical assignment where there is no reinforcing artillery being the following:

(a) Phase I. Attack of the outpost position. Missions: counter artillery by one battalion, direct snpport fire by two battalions, with special attention given to the troops of the main effort.

(b) Phase II. From the occupation of the outpost line of resistance to the opening of the artillery preparation. Missions: counter battery, harasing, and interdiction fires.



(c) Phase III. The artillery preparation.
1. Duration one to two hours.
2. Subdiviswns (approximate).
½ hour of fini Car adjustment (ranging) in daylight.
½ hour for wire-cutt ing accompanied by slight counterbattery.
½ hour of fire on infantry position.

(d) Phase IV. The attack.

Mission: direct support fires with particular attention to the main effort.

(2) All the division artillery deploys for the attack of the outpost line of resistance. The artillery positions are pushed forward to within 500 to 800 yards of the infantry line of departure so as to be able to support the attack of the main position without moving. At the time of the attack on the main position, 1 or 2 artillery companies often are attached to the main effort as accompanying artillery.

(3) The ammunition allowance for the light artillery in an attack of a position is usually 3 to 3% days of fire (l day of fire 75-mm equals 300 rounds).

(4) Two to three airplanes normally are attached to the artillery for observation and command purposes.

(5) Implied gunnery methods seem to be elementary, with main reliance on axial ground observation and with observation posts generally close to the guns. The Japanese Combat Regulation imply, however, that the artillery is capable of registering at night and oi opening fire promptly at dawn.

d. Antiaircraft artillery.

The usual attachment of antiaircraft artillery to a division appears to be a battalion, consisting of three gun companies (and sometimes a searchlight company). Such machine guns as are in this battalion are for its own local defense. In the attack of a position, the gun companies are placed in the zone of the main effort, in initial positions about 2,700 to 3,300 yards from the line of departure of the infantry.

e. Cavalry or reconnaissance.

About one platoon is normally attached to eacb wing for duty as messengers and orderlies. The remainder is divided for flank protection with the bulk on the decisive flank. As the strength of the division cavalry regiment is light, the combat value is not as great as might be expected.

f. Engineers.

Engineer missions in the typical case are: maintenance of communications; assistance to the artillery and tanks; wire cutting; and the removal of obstacles.

g. Command posts.

The average distances of command posts from the line of departure for the attack of the main positions are:

 
1 Infantry regiment 1,100 yards
2 Artillery regiment 2,700 yards
3 Division 2,700 yards
 


h. Destruction of obstacles.

The Japanese normally assume there is some wire in front of the hostile position. An attack order therefore includes provisions for cutting the wire in one of the following ways:

(1) By detailed destruction fires by the artillery.

(2) By artillery fire in the most important places, supplemented f'lsewhere by hand cutting by infantry, tanks, and engineers.

(3) By the artillery cutting the wire imperfectly at all points, with the cutting to be completed in detail by infantry, tanks, and engineers. Where there are several bands of wire, it is normal to make the destruction of the first band the exclusive duty of the infantry and engineers.

i. Medical troops.

About one-third of the medical troops are assigned to support each wing; the remainder are in reserve. These detachments set up and operate division collecting (dressing) stations located behind the regimental dressing stations. Locations are from 1,600 to 2,200 yards behind the line of departure. Two field hospitals are set up about 2,500 to 4,000 yards from the line of departure; the division is capable of setting up one additional hospital held initially in reserve.

j. Ammunition supply.

The advance section of the transport regiment (senshin shicho) ordinarily opens an infantry ammunition distributing point in rear of each wing as well as one artillery distributing point.




ASSAULT.

There is little in tactical problems which bears specifically on the conduct of the assault. While the infantry pushes ahead boldly without regard to alignment, and with bayonets fixed, the division commander influences the action by the fire of his artillery and by the division reserve. This reserve may be used to meet a counterattack, to exploit a success, or to cover the flank of a penetrating unit. The division reaches its objective prepared to pass to the pursuit in accordance with plans previously made by the division commander.


COMMENTS.

a. Characteristics.

In their concept of the attack of a position the Japanese show complete disregard of casualties in pressing it to a successful conclusion. Their campaigns initially met with a great measure of success in tropical countries because they had trained extensively in jungle terrain and adapted their technique to capitalize on what their enemies considered hindrances and handicaps. The following characteristics were common to their campaigns:

(1) Careful, meticulous staff work in the detailed planning of the operation, training and equipping of the forces to be used, and in coordinating and carrying out the action.

(2) Great boldnesses, both in the conception of the operation and in execution of its details.

(3) Fearlessness of the enemy and the ground weapons he had at his disposal.

(4) Disregard of casualties in attaining an objective.

(5) Use of surprise and deception.

(6) Refrainment from advancing to the attack pefore interdiction of all nearby enemy airfields and attainment of air superiority in the area of the attack.

(7) Great speed in infiltration, envelopment, and pursuit.

(8) Willingness to attack through terrain normally considered impassable and in adverse weather conditions.

b. Criticisms.

(1) The willingness with which the Japanese commander will order an attack on an outpost simultaneously with the attack on the main position has already been mentioned; this is done in spite of the prescription in Combat Regulations which indicates that effective reconnaissance can only be obtained after the outposts have been driven in. His shortening of the time allowed for reconnaissance and preparation has in many cases reduced the already slender chances of reaching the final objective.

(2) The deployment of the division is generally along orthodox lines, excepting that the assembly areas are invariably within effective enemy light artillery range.

(3) The plan of maneuver offers nothing of special advantage for the direction of the attack, as it usually culminates in a parallel, frontal, or semifrontal push executed by the two wings of the division, with one wing-the decisive one-somewhat stronger in infantry and artillery. However, if this form of maneuver is accepted, there is still a weakness in the absence of a decisive massing of force on a decisive point.

(4) Japanese use of artillery is subject to much criticism. The fundamental fault is that there is generally not enough of it. This weakness in ar. tillery may be the result of a lack of appreciation of the need for adequate fire support, or of a feeling that past experience has not demonstrated the need for stronger artillery. The period of daylight fire for adjustment prior to the fire for effect reduces tactical surprise and diminishes the moral effect of the preparation. This unwillingness to fire the preparation unobserved at night would suggest low gunnery efficiency. Also the absence of general support artillery reduces the flexibility of the artillery fires and limits the ability of the division commander to intervene promptly in the action by the use of his artillery. From the picture drawn in the tactical problems, one can feel reasonably sure that the Japanese infantry will jump off, even though their extensive preparations have neither destroyed hostile wire nor neutralized the enemy artillery and machine guns. The detailed workings of the direct support fires are not described in the problems studied; hence, no estimate of their effectiveness can be made other than that implied by the absence of detailed plans for infantry-artillery liaison.

(5) While the detailed administrative plan of the attack does not appear in the problems studied, such establishments as are located on the situation maps are considernbly closer to the front line than is considered standard. Lack of depth is characteristic of both the tactical and administrative dispositions of the Japanese division and has its origin in their lack of appreciation of the effect of modern fire power, particularly that of the hostile artillery. A period of contact with a well-equipped enemy may furnish correctives for this tendency.

(6) In general, although the adverse criticisms are numerous, it is not to be assumed that the Japanese will persist long in these errors, if errors they prove to be on the battlefield. The Japanese gifts for adaptation and improvisation can be counted upon to remedy quickly many of the faults in their doctrine.




PURSUIT.

a. General.

Japanese regulations and tactical doctrines place the normal emphasis on the need for pursuit to reap the full fruits of victory. They also recognize the existence of many deterring elements, such as fatigue of the troops, disorganization, and depletion· of supplies. In spite of these, the Japanese commander is urged to pursue relentlessly to avoid the need for another battle against a reorganized and possibly reinforced enemy.

b. Preparation for pursuit.

The Japanese commander throughout an engagement plans constantly for the pursuit. The enemy is ob11erved carefully, especially at night, for signs of an intenti0n to withdraw. To determine this intention, the Japanese use ground reconnaissance patrols and spies, and they may use observation aviation if it is available. When these means are inadequate, the commander is urged unhesitatingly to stage a loDal attack to gain the required information. While he is pushing this reconnaissance, he makes preparation for a possible pursuit. These preparations take the form of alerting certain units for immediate pursuit, of assembling sufficient ammunition for the operation, and of outlining a tentative administrative plan.

c. Types of pursuit.

While the quick destruction of the defeated enemy is the object of all pursuit, this cannot always be effected immediately by a single simple maneuver. In seeking to destroy his opponent, the pursuer usually will try to fix him by direct pressure while enveloping or turning one or both flanks. If this maneuver fails, he may try to push the retiring enemy off his line of retreat or into a disadvantageous position where he can be attacked more effectively. In recognition of these differing situations, Japanese writers treat the operation under two types: Type 1, where the enemy is destroyed near the field of battle where he sustained his initial defeat; and Type 2, where the enemy has partially succeeded in extricating himself, and the pursuer must take distant objectives deep in the enemy's rear after resuming semimarch dispdsitions. In both types, the destruction of the enemy is accomplished by fixing him with direct pressure, while mobile pursuit detachments, moving around the flanks, occupy the critical ·points along his line of retreat and fall upon his rear.

d. Technique of pursuit.

(1) (a) Type (1) . This form of pursuit finds its type example in the case of the daylight withdrawal of a hardpressed enemy. The withdrawal is observed by the attacker, who immediately redoubles the frontal pressure, while available reserves are quickly formed into pursuit detachments which turn the enemy's flank and fall upon his rear. Bonndaries between front-line units are readjusted as needed. The destruction of the enemy thus is accomplished in or near the original field of battle. The detailed action of the separate arms is essentially the same as in type (2), except that distant marches, with a reforming of march columns by the frontal pressure force of the infantry, are not required.

(b) Type (2).

This form of pursuit is regarded as the usual one by the Japanese. Most problems studied were of this type, wherein the enemy succeeds wholly or partially in disengaging himself and beginning a withdrawal. The initial withdrawal usually is accomplished under cover of darkness and may not be discovered at once. When the Japanese front line unit commanders find out what is occurring, they renew the attack individually and upon their own initiative in an effort to push through or around the hostile covering forces. As these Japanese units push through the enemy position, reserve units, formed into pursuit detachments, are started around the flanks with objectives deep in the enemy rear. When the Japanese front line infantry units have passed through the zone of resistance of the covering forces, the division commander halts them, organizes and sends forward additional pursuit detachments, and causes the remainder to form march columns to follow in the trace of the pursuit detachments. As this form of pursuit is considered to be usual, the subsequent remarks on the missions of the various arms apply specifically to this type, althouuh they are also applicable with slight modification to Type (1).

(2) Front-line infantry.

All units are individually responsible for discovering the hostile intention to withdraw. After such discovery, they drive into the enemy covering forces on their own initiative. In order to get through the enemy covering forces. the Japanese prefer to turn the orgimized localities by maneuver or by infiltration through the gaps. When neither is possible, a quickly organized attack on a narrow front is indicated.




Figure 83. Pursuit formation.
As the action of front-line units is decentralized, most of the division artillery is attached to front-line 1nfantry regiments. Tanks are sent in to block the enemy's retreat and to attack his artillery and command posts. To avoid a serious loss of control, the division commander usually indicates a line in rear of the probable enemy covering positions where the troops halt and reform for further pursuit. A part of the frontline infantry is then organized with previously formed pursuit dettachments. The bulk of the division reforms into march columns and follows after the pursuit detachments.

(3) Artillery.

When the enemy is discovered to be withdrawing, the artil]ery eudeavors to disrupt the enemy's retreat by interdicting (harassing) the important defiles and bottlenecks in the road net. As the front-line infantry penetrates into the covering position, the artillery, attached to infantry units, follows by bounds close behind the advancing troops and concentrates its fire on the resisting enemy infantry. Some artillery is attached to pursuit detachments.

e. Comments.

The Japanese pursuit in theory offers little variation from standard practice. Japanese regulations urge the utilization of all available transport, but, in the absence of especially attached motor transport, the division has been incapable of giving the required mobility to the pursuit detachments.

The well-known marching power of the Japanese infantry can be counted upon to compensate in a measure for this deficiency in motor transport. The pursuit is a form of operation thoroughly in line with the offensive spirit of the Japanese Army, and the war in China has shown that the Japanese pursue just as vigorously and unhesitatingly as their regulations prescribe. The North China campaign was particularly rich in examples of rapid pursuit.

In the advance down the Pinghan and Tsinpu Railways, the Japanese put their pursuit detachments on freight cars and sent them far into Chinese territory, while the main body of the divisions followed partly by rail and partly by marching. Where rail transportation was not available, the Japanese organized special motorized units (kaisoku butai) to give rapidity to their pursuit.




RIVER CROSSING.

a. General. (1)

Japanese river crossing methods are essentially those of other Armies. Success is sought through surprising the defense by concealment of preparations and rapidity of action after the crossing starts. Normal attachments to a division contemplating a river crossing include units of antiaircraft, observation aviation, engineers, artillery, and armored cars.


(2) The advance to the river is made on a broad front and is preceded by advance detachments to drive back enemy patrols from the near bank and to seize existing bridges, bridging materials, and boats. The aviation reconnoiters both banks of the river, while the Engineers conduct a detailed reconnaissance for po sibl ferry and bridge sites, and for local engineer supplies.

b. Comments.

The river crossing methods described are in general so orthodox as to occasion little comment. However, the pooling of all the Engineers into a unit in general support of the crossing is a deviation from the usual method of attaching Engineers to the crossing commanders. The weakness of the division artillery makes extremely difficult the support of an operation on a wide front such as a river crossing. It becomes difficult to allot any artillery to the distant feint, without which there cannot be much deception. The use of the reserve to create false activity, and the strict measures taken to control spies among the civilian populution, are farther exivnpl of the empha is placed on secrecy and deception in all Japanese operations.

Figure 84. Typical river crossing.



NIGHT ATTACK.

a. General.

The Japanese Army has a strong partiality for the night attack. This form of combat favors the bayonet fighting stressed in infantry training and tends to cover the weaknesses in artillery and cooperation of the combined arms which have characterized the Japanese Army. The Japanese are farther encouraged in their faith in night attacks by successful experiences in the Russo-Japanse War and subsequent operations in China and during the early part of the present war. The night attack sometimes is referred to as "a specialty of the Japanese Army" and as "a traditional Japanese method."

b, Advantages and disadvantages.

The advantages attributed to the night attack are avoidance of losses, concealment of movement, and rapidity in closing with the enemy. Disadvantages conceded are loss of cooperation between units, loss of unified direction, a greater chance of mistakes, and confusion. The Japanese believe trained troops · can overcome these disadvantages and succeed even when opposed by superior numbers. Thus, in justifying a night attack, there is a tendency to reason, "The enemy is too strongly organized or too numerous for us .to hope to defeat him in daylight; only by a night attack have we any possible chance to defeat him and accomplish our mission."

c. Occasions for night attacks.

(1) Night attacks are considered appropriate for units varying in size from company to division. Orthodox situations calling for night attacks are the following:

(a) A large unit (division) wishing to extend or complete a success during a daylight engagement may continue the attack at night.

(b) Large units (divisions) may use a part of their force to seize by surprise points needed to assist the attack of the following day.

(c) Local night attacks may be used to distract or mislead the enemy and to conceal Japanese activity elsewhere (for example, a night withdrawal).

(2) These three occasions mentioned above are referred to as orthodox since they are the ones described in Japanese Combat Regulations. In practice the night attack has been used in the following additional situations:

(a) By a large unit to prevent a hostile night withdrawal or to complete the defeat of the enemy before he could be reinforced.

(b) When superior fire power of the enemy prevented the reaching of attack objective in daylight.



d. Hour of attack.

Combat Regulations indicate that the period just after dark and just before daylight are desirable hours of attack. In 4· peacetime exercises the hours were, dusk, 2400, 0030, and 0200. The considerations involved in choosing these hours were that the engineers need at least 2 hours to cut paths in the hostile wire prior to the attack and that the objectives should be reached shortly before dawn to allow a coordinated renewal of the attack from the new line of departure a little after daylight.

e. Reconnaissance.

Regulations insist on the importance of a thorough knowledge of the terrain on the part of all commanders involved in night

Figure 85. Battalion in night attack.
d. Hour of attack.

Combat Regulations indicate that the period just after dark and just before daylight are desirable hours of attack. In 4· peacetime exercises the hours were, dusk, 2400, 0030, and 0200. The considerations involved in choosing these hours were that the engineers need at least 2 hours to cut paths in the hostile wire prior to the attack and that the objectives should be reached shortly before dawn to allow a coordinated renewal of the attack from the new line of departure a little after daylight.

e. Reconnaissance.

Regulations insist on the importance of a thorough knowledge of the terrain on the part of all commanders involved in night attacks. Japanese commentators stress the need of detailed information as to the location of enemy strong points, machine guns, obstacles, searchlights, etc. In observed peacetime practice, however, the time allotted for reconnaissance was usually quite short. Concrete examples noted were:

(1) A regimental commander, hard pressed in a meeting engagement, decided at 1530 on a night attack at dusk, less than 4 hours later.

(2) In two separate map situations, two brigade commanders decided at 1600 and 1700, respectively, while in the course of attacking a prepared position, to make a night attack shortly after dusk of the same day. These decisions are believed to have been made at such time and under such conditions as would preclude much real reconnaissance.

f. Objectives.

(1) "The objectives of a night attack are limited and are shallow in comparison to those of daylight attacks." (Japanese Combat Regulations.) Each subordinate unit receives terrain objectives as clearly defined as possible. Villages are avoided, since they are difficult to attack at night.

(2) Objectives assigned are often ambitious. The boundaries of tactical localities assigned frequently are not clearly defined features which guarantee against errors in the dark. The final objective is usually the rear edge of a position about 1,100 yards deep. Apparently about half of this is believed enough for the first bound. It will be seen in the discussion of attack dispositions that this depth of objective requires a night passage of lines on the first objective, Advance infiltration units usually precede the main attack to neutralize the enemy.

g. Conduct of attack.

(1) Infantry. (a) The infantry of a night attack usually is disposed in two assault echelons and a reserve. If the objective is shallow, one assault echelon may suffice. In the normal situation, however, a first wave rushes forward and seizes the line which constitutes the first objective; the second wave passes through the first and moves on to the second objective. This second wave also has the missions of repulsing counterattacks and destroying enemy searchlights. The relative strengths of the first and second waves depend on the relative strengths of the first and second positions. In general, a force of from one or two platoons, commanded by an officer, is given the mission of attacking and occupying a definite enemy strongpoint. A battalion generally attacks in a 450 to 550 yard sector, with 2 rifle companies in the first wave, 2 companies less a platoon in the second wave, and a platoon in battalion reserve. The battalion is expected to reach and occupy 2 objectives, the more distant being some 1,100 yards from the jump-off line. Where the rear objective is more distant than this, or the going is more difficult, 2 battalions may attack in column, the rear battalion being responsible for the taking of the second objective. The following is a schematic representation of a typical attack formation,

(b) In the foregoing dispositions, companies 1 and 2 are in a line of platoons, each platoon being in a line of squad columns; companies 3 and 4 are about 100 yards behind the leading companies in a line of platoons, each platoon in a column of squads. Exact intervals between platoons are not known, but the frontage of a company is relatively narrow, about 100 to 175 yards. The battalion reserve follows the preceding company at about 50 yards. While the Japanese recognize that this dense formation is highly vulnerable to fire, they consider it justified by ease of control and effectiveness of shock action.

(c) The infantry assault is with the bayonet without firing. Battalion guns may be used against searchlights and obstacles, and machine guns will participate in protective fires.

(2) Wire-cutting, gas, and smoke. Engineers are attached to the assault battalions for cutting lanes through the enemy wire. This cutting starts secretly after dark, about 1 ½ to 3 hours before the attack. About 3 lanes per battalion apparently are considered sufficient. If gassed areas are to be encountered decontaminating detachments precede the assault; chemical detachments for laying smoke screens also may be pushed forward if the enemy searchlights are troublesome.



(3) Artillery.

(a) Night attacks are classified as "kishu" and "kyoshu." The first is translated as "attack by surprise" and the second "attack by force." Attack by surprise (kishu) is characterized by an infantry rush with bayonet, but without a preparation or accompanying fires by the artillery or infantry weapons. Attack by force (kyoshu) implies coordinated accompanying fires and possibly a preparation. The attack of the first objective is an attack by surprise (kishu), unless the enemy is thought to be expecting a night attack; the attack of the second objective is an attack by force (kyoshu).

(b) A battalion of artillery normally supports an infantry regiment. The artillery commander, after conference with the commanding officer of the infanntry, prepares fires to be available on call during the attack. The usual method of all is by rocket. In preparing Jhe special consideration is given to possible enemy counterattacks. The artillery may be required to cut wire, but this is is costly in ammunition.

(4) Maintenance of direction. Maintenance of direction at night, being difficult, requires special measures. Devices used are;

(a) Compass bearing.

(b) Road markers, such as white stakes, strips of paper, lines of chalk or flour, and ropes.

(c) Flares.

(d) Searchlights.

(e) Shells fired for direction of artillery.

(f) Rear lights giving for direction by alignment.

(g) Company commanders wearing two crossed strips of white cloth on their backs; lieutenants, a single strip.

(5) Comments.

(1) An enemy facing the Japanese Army may expect to receive frequent attacks at night, at least until this form of combat proves definitely unprofitable. Factors favoring the success of such attacks are:

(a) Detailed training in night marches, maneuvers, and attack.

(b) Special emphasis placed on the use of the bayonet and hand-to-hand fighting.

(c) Emphasis placed on the element of surprise in the execution of night altacks.

(d) Constant use of infiltration outflanking movements and atlacks from the rear in country where cover is dense.

(2) It is believed that the Following defects will militate against the success of the Japanese night attacks in the face of an alert enemy:

(a) An overreadiness to attack at night in the hope of retrieving a check received in daylight fighting.

(b) Insufficiency of time allowed for reconnaissance, planning, and distribution of orders.

(c) Over-ambitious objectives.

(d) Mass attack formations highly vulnerable to enemy fire.

(e) Reserve units following on the heels of assault waves where they would soon be lost to control of the commander.

(f) Inadequacy of artillery support to neutralize enemy automatic weapons and to cover the operation with protective fires.

(g) An attempt to execute a night passage of lines in the course of an attack.

(3) Against an enemy who has not been determined to hold al all cost, the night attack has had and may be expected to have many successful applications. However, against a vigilant enemy strong in automatic weapons, it has proved costly to the Japanese.




SECTION III. DEFENSIVE.


GENERAL.

a. Japanese attitude.

The defensive form of combat generally has been distasteful to the Japanese and they have been very reluctant to admit that the Imperial Army would ever be forced to engage in this form of combat. So pronounced has been their dislike for the de£ensive that tactical problems illustrating this type of combat are extremely rare.

b. Object.

The object of the defensive is to inflict on the superior hostile forces such losses by fire power, disposed appropriately on the terrain and behind man-made defensive works, that the initial disparity of forces becomes equalized to the point of authorizing a passage eventually to the offensive.

c. Doctrine.

The old Combat Regulations (Sento Koyo), superseded in November, 1938, based discussion of the defensive on the active defense. Then WCI' I' gulation (Sakusen Yomurei) takes the passive defense, assumed in the presence of overwhelmingly superior forces, as the typical case, of which tbe active defense is a variant calling for special discussion. This latter viewpoint is definitely contrary to former practice where a return to the offensive is always present in the plans for the defense, even though the initial dispositions are not those of an active defense in the true tactical sense of the word.

This indicates a change in official emphasis, but probably means no real change in the practice of the defense, since in actual combat and in illustrative problems there is always present the characteristics of active defense.




DEFENSE OF A POSITION.

a. Selection of the position.

The qualities sought for the main battle position (observation, protected flanks, fields of fire, covered lines of communications, obstacles, etc.) are those standard in all schools of military doctrine. In accordance with the current trend, the Japanese emphasize the importance of antitank obstacles across the front and flanks of their position. In the presence of an enemy who may use gas, the main line of resistance will avoid depressions where it is likely to accumulate.

The importance of cover and concealment is fully recognized. Reconnaissance for the position is made by the division commander, assisted by his artillery and engineer commanders as well as other appropriate staff officer.

b. Occupation of the position.

(1) When the general outline of the position has been determined, the division commander directs the subordinate elements of his command to their respective defense areas where they deploy directly upon the position which they are to occupy. The division commander directs his cavalry (often reinforced by some infantry) to cover tho deployment and organization of the position.

This force takes position far enough in advance of the area to be organized to keep hostile artillery fire off the main line of resistance. The division commander's reconnaissance must include:

(a) Determination of the probable direction of hostile attack.

(b) The probable direction of a division counterattack or counteroffensive.

(c) Antitank measures.

(d) The assignment of troops within the defensive area.

(e) The use of artillery including antiaircraft.

(f) The composition and location of the division reserve.

(g) The use of tanks.

(h) Communications and liaison.

(i) Supply.

The completeness of the reconnaisance is dependent on the time available. He then issues hi defense order.

c. Organization of the position.

(1) The defense is based on a main position (shujinchitai) which is held to the last extremity. The division commander normally divides the defensive position into the right and left sectors ( chiku) the defense of which he assigns to hls two senior infantry commanders. In cases where the front is unusually broad, or a counter-offensive is planned, he may add a center sector. The Infantry is disposed along the main line of resistance by units of battalions, with frontage determined by the terrain and mission.

When a broad defense is adopted, battalion centers of resistance are organized for an all-arorund, independent defense in which the lateral intervals can only be partially covered by fire. In this form of defense, reserve units, kept as large as possible, are held mobile to attack hostile elements which filter through. Battalion frontages in the broad defense along the main line of resistance may approach 3,000 yards, while the normal defense frontages average from 800 to 2,000 yards.

(2) Support and local reserve units are deployed behind the front line infantry to give the position a depth of 700 to 1,500 yards. Throughout this zone automatic and antitank weapons are echeloned in depth. sually heavy machine guns are found deployed along the support position, from which they attempt to cover the front with interlocking fires (criss-cross fires) .




THE OUTPOST POSITION.

a. The outpost position (Keikai Jinchi) is indicated by the division defense order and is garrisoned by troop dispatched by the sector commanders. The order may specif the strength of the garrison, its mission, and. manner of withdrawl. Troops on the outpost line of resistance normally pass to division reserve when relieved. The outpost line of resistance is generaily from 1,500 to 3,000 yards in front of the main line of resistance, so as to be within supporting range of light artillery. Combat Regulations tend to recommend the shorter distance so as to obtain the fire support of machine guns from the main line of resistance. However, in observed practice, the Japanese seem to attach little importance· to the uncertain support of long-range machine gun fire.

b. The normal missions of the outpost line of resistance are:

(1) to obtain enemy information by observation and patrolling.

(2) to cover the main line of resistance and prevent its surprise.

(3) to cl lay the hostile attack on the main line of resistance.

(4) to act as an advance defensive position (Zensbin Jinchi).

Missions (1) and (2) are the minimum case, where the outpost line of resistance is not much more than a line for observation and reconnaissance with little defense strength. Missions (3) and (4) frequently presenL in observed practice, imply a considerable iucrease in defensive means approaclung that of a true advanced defensive position.

c. The troops assigned to garrison the outpost line of resistance, while variable in strength with the mission assigned, are kept to a minimum. For the front of a division, 1 to 2 battalions of infantry were normal in the problems consulted. Comments on these problems indicate that about 2,000 yards for the infantry company is considered the absolute maximum extension consonant with the retention of any sort of control by the unit commander. With the usual weak allotment of troops, it is impossible to hold the line continuously. Instead, important points are occupied in some strength, while the intervals are covered by observation and fire as far as possible.

The Japanese do not expect to be able to organize a continuous system of infantry and artillery fires in front of the outpost line of resistance. With the help of attached engineers, the infantry strengthens the outpost position by defensive works to the extent permitted in the time available. ln the case of the defense on a very wide front the outpost line of resistance is reduced to a line of observers, or may even be dispensed with entirely.


ADVANCED DEFENSIVE POSITION.

a, The division commander at times may order the occupation and organization of an advanced defensive position (Zenshin Jinchi ) in the zone between the outpost line of resistance and the main battle position. The purpose of such a position is to prevent as long as possible the occupation of critical points of terrain by hostile forces near the main defensive zone, to delay the enemy preparations for the attack, and to induce the enemy to launch his attack in a false direction which will expose his flank.

The organization of a formal advance defensive position is not standard Japanese practice, although the assignment of such a mission to the outpost position is not uncommon. Typical cases where the advanced positions have been organized are:

(1) where in order to obtain observation the outpost line of resistance has been pushed well forward, leaving an important ridge in the foreground of the main battle position ungarrisoned;

(2) where an oblique position is organized between the outpost position and the main battle position, with one flank resting on the outpost line of resistance while the other rests on the main line of resistance, thus inducing the enemy to expose a flank.

b. The garrison of the advance position may come from the troops assigned to the outpost position from those of the main battle position. reinforced by machiue gun and antitank weapon . Artillery elements may be assigned SUpport missions. The delicacy o{ withdrawing this force is fully appreciated by the Japanese and the clivilian commander is cautioned to issue clear and simple mission to this force and to speedy the time and manner of withdrnwal.

C. In cases where the division commander elects not to organize an advance position, the zone between the outpost position and the main battle position is covered by observers sent fonward by the front line infantry battalions. These troops patrol the foreground, cooperate with those qf the outpost line of resistance, and execute local reconnaissance.




RESERVES.

a. Reserves are held out by all units from the company upward for the purpose of executing counterattacks. The division reserve generally varie in size from 1 to 3 battalions. Its position is initially from 5,500 to 6,500 yards in rear of the main line oJ resistance, in a sheltered positiou conveniently situated with respect to the probable counterattack of the division. Tanks often will be attached to this force. Motor transportation generally is not attached to the reserve because of the paucity of organic motor transport in the division.

b. When the division commander has planned an active defense, the general reserve as a rule will not exceed a third of the infantry strength, since front line units themselves are expected to return to the offensive at the earliest opportunity.


ARTILLERY.

The artillery is disposed in depth behind the main line of resistance so as to be able to mass its fire in support of tbe main position in the area of the hostile probable main effort. One or two artillery companies may be initially in forward positions to support the outpost positions or an advanced defensive posilion. Artillery positions generally are echeloned through a zone about 2,500 yards in depth, extending to the rear from a line about 1,700 to 2,200 yards hehind the main line of resistance. Ground observation is not considered effective under normal conditions for ranges over 5,500 yards.


COMMAND POSTS.

a. General.

Command posts generally are established in well sheltered positions in rear of th main line of resistance; that of the division is usually located at a distance of about 5,500 yards, that of the infantry group at about 2,700 yards, and that of the infantry regiment at about 1,300 yards in rear of the main line of resistance.

b. Organization of the ground.

(1) In the early phases of the reconnaissance of th posilion, the division commander gives initial instructions to his engineer regardfog the supplying of entrenching tools material. and equipment. The defense order indicates the priority of work a typical one being the following:

(a) Principal points on the main line of resistance.

(b) Fields of fire and observation posts of the main line of resistance.

(c) Obstacles in front of the main line of resistance.

(d) Communications, trenches, and personnel shelters.

(2) In tactical problems it is seldom assumed that there is time available for elaborate field works. The division usually has from about 3 hours to a half day to complete its organization of the ground. Three hourS is considered the minimum required to organize a rudimentary system of trenches and obstacles along the main line of resistance. The timework unit in engjneering calculations is the 12-man squad which is considered capable of digging about 25 yard of standing fire trench in a little over 3 hours. In situations in which the use of gas by the enemy is expected the division commander will order the distribution of protective materials at suitable points throughout the area. Stress is laid on camnouflage and the construction of dummy field works, the completeness of which is dependent upon the time available. A typical plan followed by the Japanese in the construction of the field works of a company position on the main line of resistance is illustrated in figures 86, 87, and 88.

c. Conduct of the defense.

(a) Advanced elements.

As the enemy approaches the position, he will encounter first the advanced elemen ts of the defense (the outpost line of resistance or advanced defensive position). These forward elements conduct themselves in accordance with their mission which normally directs their withdrawal into division reserve before becoming seriously engaged.

Artillery companies in forward positions delay the hostile advance cover the withdrawal of the infantry, and then fall back to prepared position in the artillery zone where they revert to the control of their Organic commander. The avalry which has withdrawn to the flank while maintaining contacL with the advance positions, will carry out its normal missions.

(b) Defense of the main line of resistance.

As the hostile infantry forms up for the attack 011 the main line of resistance, the defensive artillery brings down its counter preparation fires. Tanks may be sent forward covered by artillery to upset the preparatious of the enemy. As the hostile attack enters the zone of infantry fires, the sector commanders conduct the defense of their sectors, first by fire, then by the bayonet in front of their entrenchments.

Commander of all units connten1ttack unhesitatingly as the integrity of their positions become threatened by the hostile attack. The artillery assists the close-in defense by standjng barrages and concentration brought down within the defensive position.

(c) The counterattack or counteroffensive.

The division commander is constantly on the alert to determine the proper time for the division counterattack or counteroffensive. The favorable moment will generally be at the time the hostile attack has been stalled; when the enemy has blundered into an unfavorable position; when a favorable opportunity has been created by a successful local counterattack; and when the enemy pauses to reorganize or consolidate his position. The plan for a return to the offensive will be made tentatively well in advance of the occurrence of the opportunity. The direction of the counterattack generally will be aimed at an envelopment; however, at tinies, the situation may compel a purely frontal attack. The mass of artillery, and tanks if present, will support the counterattack or counteroffensive. The division commander may directly control the counteroffensive, or he may delegate control to a sector commander.




COMMENTS.

a. Aggressive character.

Since the defensive in Japanese regulations and military writings is branded as a negative form of combat, un-Japanese in essence and spirit, it has been very difficult to write a tactical problem for which officers were willing to advocate a defensive solution. In problems studied, the basic decision to defend already had been made by the division commander, a school device to control the offensive elan of the student officers. Even when thus forced on the defensive. Japanese officers have the return to the offensive always uppermost in their minds and are quick to launch counterattacks, large and small, coordinated and uncoordinated, on the slightest provocation. On the maneuver ground, troops are always ready to abandon their prearranged system of infantry fires to meet the attacker with the bayonet in front of their trenches. The defects of a defense so conducted are glaring to the occidental student of tactics, but its positive and aggressive character has virtues which will, on occasions, upset a careless or overconfident attacker.



Figure 86. A company position after approximately 2 hours of work.

NOTE: After approximately 6 hours of work the individual firing trenches within a squad position will be connected, forming a single line.



Figure 87. company position after approximately a week of construction time.

NOTE: Squad positions will be enlarged standing trenches. The communication trenches will be deep enough for crawling, and the shelters will be of light construction. Accommodating 6 men. Only the machine gun shelters will be built to resist 150-mm howitzer fire. The wire entanglements beyond the front lines will be 8 meters high.



Figure 88. A company position after approximately 4 weeks of construction time.

b. Other characteristics.

In spite of the usual instructions issued relative to the need of echelonment in depth of the defense, there is an apparent tendency to concentrate a disproportionate strength in the front lines. This is especially true of the special weapons (machine guns, battalion guns, etc.). The appearance of the "broad defense" in Combat Regulations appears to be a recognition of the increased strength of frontal resistance of modern infantry, as well as an official corrective to the often remarked Japanese tendency to a shoulder-to-shoulder disposition of units both on the attack and defense.




SECTION IV. RETROGRADE MOVEMENTS.


THE WITHDRAWL.

a. General.

There is little military literature obtainable to elaborate on the bare substance of the provisions of the Japanese Regulations governing the withdrawal. In general, the method of withdrawal appears to be standard. It is notable, however, the usual strong insistence on the dangers of a daylight withdrawal is not in regulations. No information has been obtained as to when the Japanese commander considers a withdrawal required or justified since, in the cases studied, the withdrawal was executed on army order and was not considered as imposed by the enemy. b. Preparations for . the withdrawal. The division commander, in anticipation of a withdrawal, first attempts to clear his rear area of supply troops and installations, improves the roads which he expects to use, and orders preparations for demolitions to delay the enemy follow-up. All preparations are made with the utmost secrecy while preserving a bold front.

c. Daylight conduct of the withdrawal.

(1) Local covering forces. The breaking of contact of the front line infantry ill done under the protection of local covering forces, disposed from 1,500 to 2,000 yards behind the firing line. These troops are obtained from battalion, regiment, or other reserves not committed to the front line fighting. The position occupied is, when possible, to the flank of the line of retreat on commanding ground permitting overhead fire in support of the retiring troops. The local covering forces give support by fire and, on occasion, may execute local counterattacks to aid in disengaging the front line infantry. About the equivalent of one regimental sector in open warfare appears to be an average strength for the local covering forces in the problems consulted.

(2) General covering force (Shuyo Jinchitai). In addition to these local detachments, the division commander organizes a general covering force behind which he reforms the major elements of his command. The division reserve is usually the principal component of this covering force which, in principle, is made up of the freshest troops at the disposal of the commander. The bulk of the division artillery withdraws and deploys behind this covering position to protect the withdrawal. The Japanese try to place the covering position at an oblique angle to the axis of retreat and from 3,000 to 5,000 yards in rear of the front line. The division command post is set up behind the covering position for the purpose of controlling the withdrawal and organizing the subsequent retirement for which the troops on the covering position eventually become the rear guard.

(3) Execution of withdrawal. Protected by the covering forces, the front line infantry withdraws straight to the rear assisted by support units• in the second echelon. The Japanese feel that it is desirable for all front line units to pull back simultaneously, but often some must hold on longer than others. The division artillery, the bulk of which already has retired to the general covering position, supports the withdrawal. In some sectors, a sudden local counterattack may be warranted in order to create a favorable situation for the withdrawal. Retreating units reform progressively, arriving by many small columns in the general assembly area behind the general covering position. Here, division march columns are formed and directed toward the final terrain objective of the withdrawal. The engineers execute demolitions to retard the enemy, while columns move off covered by a rear guard. The cavalry and aviation reconnoiter for turning movements around the flanks by pursuit detachments. The aviation may be called upon to attack ground troops which are endangering the success of the withdrawal.

d. Night conduct of withdrawal.

(1) General. The night withdrawal differs from that in daylight in the following important respects:

a. The local covering mission is performed by a "shell" of small detachments left in position on the front line throughout most of the hours of darkness.

b. Retiring units reassemble and form march columns nearer the front line than is the case in daylight.

c. A general covering position is particularily not organized . Detailed preparation in daylight is necessaTy prior to a night withdrawal. This includes a designation and marking of roads to be used by retiring units, as well as the usual clearing of the rear area. Secrecy is essential throughout to conceal the intention to withdraw.

(2) "Shell." The breaking of contact by the front line infantry is done under the cover of a thin line of infantry detachments, strong in machine guns and supported by a small amount of artillery. This "shell" simulates the usual sector activity throughout the night to deceive the enemy and, if attacked, sacrifices itself in place to protect the retirement.

Its time of withdrawal, usually about daylight, is set by the division commander. The mission of the "shell" may be facilitated by local attacks executed early in the night by front line detachments prior to their withdrawal. Normally no general covering force is needed to supplement the "shell." An exception is the case where the "shell", left in place until dawn, requires protection to get away without undue losses.

In such a case, a small general covering force, strong in cavalry and mobile troops, may be organized for the benefit of the " shell."

(3) Execution of withdrawal.

The behavior of the front line units is essentially the same as in daylight. They reform progressively as they retire, assembly areas being somewhat nearer the front line than in daylight. One or two companies of artillery remain until nearly dawn to support the "shell" and carry out normnl activity.

e. Comment.

Japanese procedure in the withdrawal is generally orthodox. The absence of the customary injunctions against the daylight wiLhchawal is symptomatic of the Japanese under-estimation of the effects of modern fire power and aerial attack. However it is unwarranted to assume that, in practice, they will not try to avoid daylight withdrawals when the situation permits.




THE DELAYING ACTION (JIKYUSEN).

a. General characteristics.

(1) The Japanese do not recognize the delaying action aa a separate and distinct form of military operation but include it in the broader term, "jikyusen" (holding-out-combat). The expression is used to cover, in addition to pure delay, a nUmber of types of operations characterized by a desire to avoid a fight to a finish, but in which the idea of delay is somewhat remote. Thus, in addition to the typical delay situations, such as the action of rear guards and overing forces, the Japanese treat under "jikyusen" demonstrations reconnaissances in force, and night attacks designed to cover a withdrawal. In tbe subsequent discussion,an effort is made to disregard the elements not bearing directly on delay which the Japanese inject into the treatment of "jikyusen."

(2) The usual purpose o{ delaying action is to gain time to contain or to divert a superior enemy while avoiding decisive combat. "Although. these ends are frequently achieved by defensive action, there are occasions when the mission can be accomplished only by offensive action." The proceding sentence is a literal translation from the Sakusen Yomurei. Elsewhere, the same regulation urges that even when defensive measures are initially better adapted to the situation, the commander must always be ready to take advantage of an opportunity for offensive action. However, when offensive action is indicated, in order to avoid becoming deeply engaged, the division commander designates limited objectives and rigidly controls the number of trooPs comm1tted to action. In comparison to the meeting engagement, fronts of deployment are wide in such an offensive action.

(3) Mobile troops, well equipped with automatic weapons and artillery, are best adapted to delaying actions. The infantry fire fight generally takes place at long ranges as the engagement is broken off when the enemy draws near. Frontages are wide, and the breadth is obtained by increasing the intervals between occupied key positions. Reserves are kept large to cover withdrawals, to give continuity to the resistance of the delaying force, and to provide troops for such limited offensive actions as the commander may undertake.

b. Choice of a delaying position.

While the situation may force the commander to seek the required delay on a single position, such a disposition creates a danger of becoming involved in a fight to the finish or in a costly withdrawal at close range from the enemy. It is thus preferable to delay on successive positions separated by about two to three miles. A delaying position is chosen for its observation, distant fields of fire, and covered routes of withdrawal.

c. Conduct of the delaying action.

(1) When the decision has been reached to delay an advancing enemy, the division commander sends out his cavalry to establish and maintain contact and initiate the delaying action within limits of its combat capacity. He then selects the position or positions upon which he expects to gain the required time for the accomplishment of his mission. He often will send forward an infantry detachment of from 2 companies to a battalion to occupy an advanced position ahead of the first delaying position. Such an advanced position is located within range of artillery support from the delaying position in accordance with the principles for choosing an outpost line of resistance. These forward troops assist the cavalry, as the latter falls back to the flanks of the delaying position, and impose some loss of time on the advancing enemy.

(2) The enemy is taken under fire by the division artillery at extreme ranges. Artillery positions are close behind the infantry, and are grouped together for ease in fire direction in the belief that there is little to fear initially from the hostile counterbattery. Eventually, the infantry machine guns join in the fire fight as the enemy comes within range.

(3) The division commander makes every effort to hold out a large reserve. In cases noted, this amounted to from a third to a half of his infantry and a battalion of artillery. The main purpose of this large reserve is not to counterattack ( although some of it on occasion may engage in local offensive action) but to reconnoiter, prepare, and occupy the next delaying position from which it covers the withdrawal of the troops of the first position. The Japanese thus contemplate, in effect, delay on successive positions occupied simultaneously, although this form of action is implied rather than clearly defined.

(4) The engineers of the division find their principal missions in road maintenance, route marking, and the preparation and execution of demolitions. The last are carefully planned to cover the flanks and routes of direct approach to the delaying positions.

(5) As in other forms of combat, the Japanese count heavily on measures of deception to assist in accomplishing the delaying mission. Devices used to create this deception are:

- dummy engineer works;
- demonstrations;
- economy of force in wooded and covered areas while strength is displayed in open terrain;
- roving artillery;
- proclamations;
- propaganda.

All these measures aim to create an impreasion of strength which will cause the enemy to adopt a cautious attitude toward the delaying force. In spite of the fact that such measures impose fatigue on the troops and, in extreme cases may lead to a serious dispersion of effort, the Japanese feel that their use is justified.

d. Withdrawal.
The troops on the delaying position retire on order of the division commander while the enemy is still at a distance unless the mission specifically required a long delay on a single position. When the hostile infantry gets within l,000 yards of the position it is considered time to go, and the troops on the next delaying position cover the withdrawal. Detachments left in the zone between the positions effect intermediate delay. When it has not been possible to prepare and man a second position, the division commander tries to put his withdrawal until nightfall.

e. Comments.

(1) As a defensive form of combat the delaying action does not appeal to the Japanese soldier who thinks first and Last of fixing bayonets and moving forward. Influenced by the strength and weakness of this psychology, the Japanese commander often will choose offensive action when the defensive is better suited to the immediate situation. It has been noted that a little fresh encouragement has been given in the new Combat Regulations to the use of offensive action to obtain delay, an encouragement of which Japanese commanders can be expected to take full advantage in order to seek delay through attack. It is felt that this over-aggressiveness may ill serve the usual purposes of delay.

(2) The injunction to hold out a large reserve does not agree with the usual teachings on delay. A reserve suggests the intention to counterattack, whereas a delaying position usually is abandoned before the enemy has come within counterattacking range. ln the practice of map problems, this large reserve waa alwaya used to occupy a rear delaying position so that the operation hecame, in effect, a delay on successive positions simultaneously occupied. Thus, the requirement of holding out a large reserve, in spite of its apparent contradiction, becomes reconciled with tactical orthodoxy.

(3) The Japanese dislike for using their light artillery at long ranges tends to keep successive delaying positions relatively close together (3,000-4,000 yards) . It is generally considered that 5,500 yards is the extreme limit of effective terrestrial observation, and it is rare to assign missions beyond that range. Japanese artiller has had little experience in fire with air observation.

(4) It is reasonable to suppose that the Japanese have learned the latest methods of withdrawal as employed by modern armies which place great emphasis on the use of tanks, mobile artillery, motorized infantry, mines, tank traps, aircraft, and a new concept of distance.




SECTION V. EMPLOYMENT OF TANKS AND MECHANIZED UNITS.


GENERAL.

a. Background.

As a result of experiences- in the Manchurian Incident, the war in China, and the clash with the Russians at Changkufeng, the Japanese Army has acquired a lively appreciation of the value of mechanization. Much thought was given to the proper use of this new weapon in the light of the experiences of the Japanese and German Armies. A distinguishing feature was the early modification, extension, and detailed expatiation on the paragraphs devoted to the use of tanks and mechanized units in combat regulations. However, the new changes in regulations, while giving additional space to mechanization, treat the subject with broad generalities which leave considerable doubt as to whether the Japanese have worked out many of the practical details of such highly involved questions as infantry-tank-artillery liaison, control by higher commanders, and logistics of mechanized forces.



b. Estimated strength.

(1) At the outbreak of the present war, the known mechanized strength of the Japanese Army consisted of at least 4 tank regiments. While the wartime expansion of tank units is not definitely known, it is believed that there are now additional tank regiments. The reliance on cooperation with the infantry may explain the large number of "Independent" armored units, which can be attached to other formations as and when required. The lack, or failure, to identify artillery, infantry, etc., with the Tank Group also may be explained by this policy, and this formation may, in fact, be more of the Army Tank Brigade type than of the armored division. This view again is borne out to some extent by Japanese teaching, and it is thought that the Tank Group may be employed in conjunction with infantry formations, working in close cooperation with infantry divisions, rather than fulfilling the role of an armored division, which would be to destroy enemy armored formations. It is believed, however, that there are at least 2 armored divisions in Manchuria at the . present time.

(2) Weight for weight, the speeds of Japanese tanks do not compare unfavorably with those of other Armies, but it is considered that these speeds drop rather more appreciably across country than do those of Allied tanks. The Japanese tanks are bulkier for their weight since their armor basis is smaller. This can be accounted for by the fact that the Japanese regard their tanks as infantry support weapons, and therefore they rely on the infantry to neutralize the enemy anti-tank weapons.

c. Tactics.

Our very limited experience with Japanese tank tactics in Burma and the South West Pacific Area leads to the conclusion that the Japanese regard the tank primarily as a close support weapon for the infantry. Only on one occasion did a small tank versus tank action develop; even then the Japanese tanks are believed to have been surprised during a reconnaissance, and not to have been seeking the armored battle in which they were so badly out-fought. There is little doubt, however, that the Japanese have carefullv studied the tactical trends of tank warfare in Europe, and, while industrial limitations make the general employment by the Japanese of large tank organizations unlikely, should they fight in suitable terrain, they reasonably may be expected to employ armor at least as a spearhead to infantry enveloping attacks. Should the nature of the ground permit, the Japanese have, the tank, an ideal weapon for exploiting their favorite maneuver of a wide and rapid encircling movement which cuts the enemy's lines of communication and generally disorganizes his rear areas. With the Battle of France before them, it is unlikely that they would neglect the advantages gained by the use of armor in this, their favorite offensive maneuver.


TRAINING.

Japanese tank troops are highly trained in night fighting, and in fighting under extremes of weather. They are obsessed with the value of the attack, and creWl! will not hesitate to leave their tanks to fight on foot when pressed or in coming up against manned obstacles. Japanese tank training stresses the need for:

(1) rapid decisions;
(2) rapid mobility;
(3) rapid concentration of fire;
(4) concealment of intentions; and
(5) supply and repair.

Frequent practice is given in maneuvers over varied ground; in developing close cooperation within the tank between driver and gunner; and in bringing accurate fire to bear in the shortest possible time. In combat training successive stages are the advance, deployment, attack, mopping-up, and pursuit.




TANKS WITH THE DIVISION.

a. Offensive.

(1) The tanks with a division are normally used as accompanying tanks attached to the infantry units making the principal attack. Prior to the attack such tanks are brought up secretly to assembly positions about 3 miles behind the line of departure. Here final reconnaissance and attack preparations are completed.

Tank commanders confer with then infantry regimental and battalion commanders to whom they are to be attached as well as with the artillery which is to support the attack. Topics for conference and decision are tank objectives and the hour of attack; tank jump-off positions, roµtes to the jump-off position and the subsequent zone of advance; type of artillery support desired and its coordination with the advance of the tanks; plan for meeting a counterattack by hostile tanks; signal communications between infantry, tank, and artillery.

On the night preceding the attack, the tanks move to jump-off positions under cover of the noise of artillery firing and low-flying airplanes. Attack formations aim at obtaining the effect of mass by disposing the tanks in several waves across the front of the infantry unit to which they are attached. The tanks move forward, followed closely by the infantry and supported by the artillery which neutralizes enemy antitank weapons by fire and smoke. Tank objectives are:

obstacles blocking the advance of the infantry; the enemy automatic weapons left unneutralized by the artillery; and eventually, the hostile artillery and command system. The infantry must stick close to the tanks; if the latter get too far ahead, they may have to turn around and rejoin the infantry.

(2) The foregoing discussion appljes particularly to the attack of a position where the need for tanks is especially acute. In the meeting engagement, the tactics of the tanks are in general the same, except that preparations and liaison arrangements are not so detailed, and the attack moves more rapidly. Also, in a favorable situation, the division commander, prior to the main attack, may send out all or part of his tanks ahead of the advance guard to upset the hostile deployment and derange the command system of the opposing force. In such a case the tanks are given a rendezvous point where they assemble and return to the main body in time for use with the principal attack.

(3) The peculiar local conditions of the war in North and Central China caused certain additional uses to be made of accompanying tanks. In the case of the attack of a walled town. the tanks moved out ahead of the infantry and cleaned up the outer defenses of the town gates. Then, while the infantry closed in to assaulting range, the tanks stood by close to the wall and neutralized the defenders of the rampart by the fire of their machine guns. After the infantry entered the town, the tanks again led the way and assisted in mopping up hostile elements that continued to resist. Such use of tanks is possible only against an enemy weak in antitank weapons.

(4) Leading tanks. It is doubtful whether the Japanese have had actual experience in the use of leading tanks, although the new Combat Regulations contemplate their use in cases where tanks are available in plentiful numbers. The Japanese first satisfy the requirements for accompanying tanks; those in excess of this requirement are organized into a leading tank detachment under division control. SeVeral minutes ahead of the main attack, they rush deep into the zone of the hostile artillery and command system. They are given a zone of action, a rallying point and a mission type of order that includes the subsequent course of action. Artillery support is planned carefully to cover the tanks through the forward area of hostile antitank weapons. Long range artillery coordinates its fire with the movement of the tanks so as not to interfere with their progress.

(5) Miscellaneous uses of tanks.

The following miscellaneous use of tanks have been noted:

(a) Tanks were used to break through the defenses at the mouth of a defile, reconnoiter the inner defenses, and return.

(b) Tanks executed local battlefield liaison and reconnaissance missions as well as transported essential supplies in the areas beaten by small arms fire.

(c) Tanks were used as the main force in a frontal holding attack, while the remainder of the division enveloped a flank.

(d) Tanks were used to block the escape of retreating forces through the rear gates of walled towns.

(e) In November, 1937, three Japanese tanks formed a stationary battery while infantry were crossing the Suchow Canal. In February, 1938, 40 tanks were similarly employed at the crossing of the River Hwai. A few months later, tanks were used as pursuit troops driving along both sides of the Yangtze at the same time. In 1938, during the attack on Suchowfu, tanks made a wide circling move and cut the railway lines nearly 40 miles from the city.

(f) Against road blocks the Japanese used their tanks to pin down the troops covering the block, while the infantry tried to infiltrate and attack from the rear and flanks. In Malaya, whenever the infantry was held up, the Japanese brought up tanks to support the attack, overcoming any obstacles caused by demolitions, or ferrying tanks over fastflowing rivers. Normally, they attempted to force the tanks through frontally, and, when successful, broke in among the troops on both sides of the road. When the tanks were held up frontally, they were brought in on the flanks. At the battle of Slim, Malaya (1942), the Japanese attacked with 30 tanks. These moved parallel to . the main highway for several miles through roads of the adjacent rubber plantations and then cut in to the main road, moving straight down it to a depth of 20 miles.

(g) At Milne Bay a few light tanks were used as were about 12 on Guadalcanal. On each occasion their use was restricted by the terrain, but on neither was there any outstanding tactical employment.

b. Defensive.

On the defense, the division commander usually holds his tanks initially in division reserve, under cover from artillery fire and attack from the air. Eventually they are attached to the infantry making the division counterattack. They are considered particularly valuable in stopping a hostile mechanized force, for the defensive tanks can defeat a superior number of the enemy's if the latter have run away from their artillery support or have become dispersed. Occasionally, the defending commander may use his tanks in a raid on the hostile assembly areas before the enemy attacks. In all cases, tank actions must be supported by carefully arranged artillery fire to neutralize the hostile antitank guns.




MECHANIZED UNITS.

a. Organization.

In China the Japanese have used provisional mechanized units, varying in size and composition according to the material at hand and the mission to be accomplished. In general, these units have a strong nucleus of tanks, supported by motorized infantry, engineers, field and antiaircraft artillery, antigas, and signal detachments. The whole force is supplied by a truck train formed from line of communication (heitan) supply units. Observation aviation is usually attached.

b. Tactics.

(1) Offensive.

(a) A mechanized force normally receives an offensive mission whereby advantage can be taken of its high mobility and capacity for independent action. In general, its tactics are about the same as those of a large cavalry force. By secrecy and rnpid movement (usually at night) it surprises the enem foTce in a terrain suitable for the tanks which form the backbone of the combat strength of the command. The commander, keeping his tanks under central control, masses them for a quick blow in a vital attack direction.

The motorized infantry receives any or all of the following missions:

(1) It covers the tanks and facilitate their action.

(2) It holds the grouud won by the tanks.

(3) It occasionally takes over a front in a holding attack or makes an attack to create a diversion either by day or night. The infantry always fights dismounted but stays in its carriers as long as possible. The artillery performs normal support missions with special attention to enemy antitank guns.

(b) As a mechanized force draws near the enemy, the commander prepares tentative plan to meet varying hypotheses as the situation is susceptible to sudden changes in this fast-moving type of combat. He activates reconnaissance and security agencies, meanwhile gradually reducing the depth of his dispositions. As the enemy situation clears somewhat, he chooses an assembly area in conformance with his tentative scheme of maneuver.

This area is as close to the enemy as is consonant with safety. If there is danger of a sudden collision with the enemy, the commander may traverse the final distance between himself and the enemy by bounds from one terrain line to another.

(c) A bold envelopment or turning movement is the maneuver best suited to a mechanized force. Such a force often will march at night, assembled in darkness, and attack at dawn. In the assembly area, reconnaissance is made, order is restored, and missions are assigned for the subsequent attack. When the enemy situation is vague, the usual objective is a terrain feature the possession of which is essential to the enemy. In the final deployment troops remain in vehicles until the danger of hostile fire forces them to dismount. When this has occurred, empty vehicles are parked under cover from air and ground observation. The unit reserve is usually infantry but on occasion may include some tanks. The detailed conduct of the attack follows the tactics of a large cavalry force.

(d) Mechanized units are particularly well adapted to pursuit and exploitation. The objectives assigned to them are those suitable to any pursuit force, but their range of action permits a deepr penetration into the hostile areas. It is in this form of action that the Japanese mechanized forces have found their chief employment in China. Examples abound in which such units have cut the roads and railroads behind a Chinese front on the verge of collapse and have assailed the hostile rear. The broad plateaus of Suiyuan and Chahar have afforded a terrain particularly favorable to such armornd tactics.

(2) Defensive.

Since the defensive nullifies the mobility of a mechanized force, it is a form of combat to be avoided. However it may be imposed by the situation. In such a case, the commander usually disposes his dismounted infantry in a discontinuous line of strong points, with most or all of the tanks held in reserve. The defense is conducted along customary lines, with the principal concern of the commanders being the engagement of his tanks in a counterattack. In the usual defensive situation the enemy will be superior in tanks; hence, the commander must endeavor to stage the decisive tank action out of range of the hostile artillery but within the range of his own antitank guns. Under such conditions, his inferiority in tanks is compensated for by the supporting fires of his artillery. When the hostile tanks are defeated the crisis is passed and the counter-offensive often is justified.


COMMENTS.

The value of mechanization is fully appreciated by the Japanese Army and its armored tactics should not be taken lightly. It has acquired considerable battlefield experience in small scale tank action and in the use of improvised mechanized forces. Such units as have been encountered do not have the striking power of the elaborated mechanized forces of Western powers.





PART II - APPLICATION OF TACTICS.

SECTION VI. ANTIAIRCRAFT.


GENERAL CLASSIFICATION OF JAPANESE ANTIAIRCRAFT MEASURES.

a. Passive.

Passive antiaircraft measures consist of concealment, camouflage, and dummy works. By these means, an attempt is made to hide the defended object from air observation, to make it look like either a natural part of the terrain or a non-mili- tary objective, or to con truct dum:my works so that Lh y wjll chaw the fire of attackjng aircraft. Frequently ombinations of thf,se methods are used. On the whole, camouflage in the field and of small installations has been excellent, while attempts at camou!lage of large installations so far covered have not been parli cularly successful. Manuals place consiclerabl mphasis on th use of hoth large and small-scale smoke screens. but this has not so far been observed in practice: b. Active.

Active measures in general are as follows:

(1) Antiaircraft guns of calibers ranging from 7.7-mm to 127-mm are known to be in use. These are high velocity weapons with effective ranges up to altitudes of 25,000 feet. They are used for direct action against attacking planes, to shoot them down and to break up their bomb runs. Ammunition ranges from incendiary to high explosive fragmentation projectiles with time fuses.

(2) Barrage balloons are used for protection against dive bombers. These are usually camouflaged a greenish blue when defending objects on the water, and are difficult to see. They offer no protection against high level bombing, because their maximum elevation is not great enough-usually being about 1,000 feet.

(3) Night fighter planes, equipped with radar or operating in conjunction with ground searchlights, are used to seek out and destroy hostile planes.




ORGANIZATION.

a. Areas to be defended.

Areas to be defended are:

(1) important points, such as bridges, beachheads or docks, anchorages, isolated military stores, and movement of troop columns thru defiles;

(2) important towns or cities;

(3) airfields. No definite priority can be placed on these areas, for it depends on their relative importance which is subject to change.

b. Home defense.

For active defense, the Japanese homeland is divided into antiaircraft defense areas. The organization of defense measures is usually entrusted to the senior Army officer in the district who coordinates the efforts of military, naval, and civilian units. The Army units include the fortress artillery of fortified zones, individual units of field antiaircraft artillery, and army aircraft.


SEARCHLIGHTS, FIRE CONTROL INSTRUMENTS, AND WARNING METHODS.

a. Searchlight tactics.

(1) At the end of 1943, Japanese searchlight operation was still ragged and inefficient compared with Allied standards. However, they were rapidly improving their methods. There were indications that some type of radio direction finder for searchlights was coming into use by the Japanese in certain areas. Reports state that some Allied aircraft have been picked up as soon as the searchlights w~re turned on and illuminated for as long as three minutes, even when evasive action was taken.

(2) It is believed, however, that the majority of Japanese searchlights are directed by sound locators.

(3) Lights apparently are controlled centrally, as they are frequently illuminated simultaneously, searching in the same direction.

(4) Cooperation between searchlights and night fighters has improved. Searchlights have frequently been seen waving vertically or scissoring, especially when about to focus on a plane. Searchlights have been waved together vertically on one side or the other of hostile aircraft, presumably to give direction to a night fighter.

(5) Emplacements are generally circular and from 15 feet to 35 feet in diameter, with most being of the larger size. Searchlights are generally emplaced in an oval pattern with the defended area in the center.

b. Fire-control instruments.

(1) Japanese fire control instruments examined to date show no new improvement, and in general, they are obsolete judged by modern standards. The standard heavy antiaircraft (75 mm.) guns recovered in the Aleutians, the Solomons, and New Guinea were all manually operated from data transmitted by voice to the gun crew members from the operators of off-carriage instruments. No directors have been used in conjunction with the 40 mm, 25 mm, or 20 mm automatic cannons. However, reports indicate that Allied flyers have experienced heavy accurate antiaircraft fire over Japanese bases, even through cloud cover, which would seem to indicate that fire-control equipment of more advanced design is in use.

(2) It is a common practice for single Japanese planes to fly at the same altitude as enemy bombers although well out of range. These planes make no effort at interception; their evident purpose is to transmit to the guns data as to the elevation and speed of the target, for when these "spotter" planes are present, the corrections of antiaircraft fire have been rapid.



c. Warning methods.

Three warning methods are in general use by the Japanese:

(1) Sound locators of the trumpet type are still used, although they are not very effective against modern high speed planes.

(2) Radar is in use in many important defenses, but its range appears to be rather limited. Development by the Japanese in this field has lagged behind that of Allied nations. The number of occasions when Allied planes have reached their objective undetected would indicate that the use of radar is limited.

(3) Visual observers are extensively used to give warning. Outposts with the mission of reporting the movement of hostile planes are placed in advantageous positions. These outposts attempt to get as close as possible to points from which they can observe the movement of enemy planes from airfields. It must be expected that some of these groups will actually be within the enemy lines. Other observers are posted on high terrain features and on ships. They work in short tours of observation with frequent relief, and report plane movements by radio. Their equipment for observation is usually limited to binoculars. There are instances where the only warning system employed consisted of the gun crew itself, acting as observers.


POSITIONS.

a. Location.

(1) Japanese antiaircraft companies· observed are usually situated within a 1-mile radius around the area to be defended, with the greatest concentration of guns between the defended areas and the sea approaches thereto, along shore lines, and in the direction of enemy territory. Guns are mounted both in single positions and in batteries of from 2 to 12 guns. The distance between guns in both heavy and medium companies varies from 40 to 250 feet, with the majority of revetments between 50 and llO feet apart. Machine guns usually are placed either within the group or a short distance from the group for protection against low flying aircraft.

(2) The only distinction between the locations of medium and heavy antiaircraft companies is that medium companies are rarely placed outside the 1-mile radius except along beaches, while some heavy companies may be as far as 4 miles from the defended area.



Figure 89. Four Gun Heavy Antiaircraft Battery (Emplacements Empty). Emplacements are built of earth over which grass has grown. Pattern is a shallow arc with fire control installations in center. A three gun light antiaircraft and a two gun light antiaircraft are also present. The large emplacements could house 75-mm or 105-mm guns. The small emplacements are probably for heavy machine gun or 13-mm antiaircraft.


b. Arrangement.

In general the arrangement of the positions is dependent on the number of guns involved and the terrain. When 3 guns are used, the position is usually in the form of a triangle, with 1 gun at each corner and the command post in the center. In the case of 4 guns, the shape of the position is usually rectangular. If more than 4 guns are employed, the position is normally in the shape of a shallow arc. Small caliber, automatic guns are normally employed nearby for close in protection from low flying planes. Where the terrain permits, some gun positions may be located on commanding ground, thus providing for all around traverse. Command posts vary in both number and location relative to the gun positions. They are usually located inside and near the mid-point of the battery pattern.





Figure 89a. Continued from above.



Figure 90-91. Note the rough trapezoidal pattern this four gun Heavy 75-mm Antiaircraft Battery. The command post is centrally located. This pattern is used most often at permanent, strongly established Japanese bases. The emplacements are shallow excavations with thick, strong revetments.



Figure 91. Kavieng airfield.


GUN EMPLACEMENTS.

a. Standard type.

The standard type of gun emplacement used almost exclusively is of circular or semi-circular construction, either level with the surface of the ground or slightly dug in. It is surrounded by a revetment built up of logs, coral, sand bags, and other materials to protect the gun and its crew. The opening usually is protected by a blast wall. A variation of this type of emplacement is constructed with two concentric circular revetments. (This type is commonly called the "doughnut.") The almost rigid adherence to these types of emplacements makes them readily identified from the air. Recently more care has been taken to conceal them by decreasing the slope of the revetment and planting it with natural growth so that shadows will not be so apparent.

b. Sizes.

The caliber of the gun can be determined roughly from the size of the emplacement. Approximate sizes of emplacements for certain guns are listed below:

Num Caliber Description
1 105-mm Normally 25 feet in diameter
2 75-mm mobile Normally 20 feet in diameter
3 75-mm static Normally 15 feet in diameter
4 Machine cannon Normally 13 - 15 feet in diameter
5 13-mm machine guns Normally 8 feet in diameter



c. Camouflage.

Little or no effort is made to camouflage or conceal the guns, but extensive use is made of dummy and alternate positions, even to the extent of constructing dummy guns.




EMPLOYMENT OF ANTIAIRCRAFT.

a. General, It is normal to attach antiaircraft units to divisions. Their missions are the same as those assigned in Allied armies, but the division commander is given direct control over them.

b. All antiaircrn1t guns are dual purpos , most being capable of a minus depression; however, there is no evidence of armor-piercing ammunition for the larger caliher guns.



Figure 92. Aerial photo.


c. Methods of fire.

(1) All guns in a position frequently concentrate their fire on the leading plane of a formation and fire on succeeding planes if time permits.

(2) Colored spotting rounds often are used.

(3) Instances of accurate fire above the overcast indicate the probability of radio direction equipment.

(4) In areas where the ground is often blanketed with clouds, such as in the Aleutians, all guns direct their fire at the opening in the clouds where the enemy planes may normally be expected to appear.

(5) Barrage fire has been employed.

(6) In jungle country, the Japanese have shown an increased tendency to attack with light machine gun and rifle-fire against low flying aircraft. Such fire is encountered particularly along lines of communication, and its effectiveness should not be discounted.



Figure 93. Skeych of 75-mm antiaircraft gun in earth revetment. Note partially excavated type of emplacement with high revetment and built-in Ready Magazine. Note also zigzag entrance trechs.





SECTION VII - ANTITANK DEFENSE.

1. GENERAL.

a. Background.
(1) The antitank methods adopted by the Japanese Army in antitank measures follow normal modern practice, except that the army as a whole is weak in antitank weapons. More thought, however, is given to the simpler forms of antitank defense, such as the use of antitank mines, incendiary grenades, gas grenades, obstacles, and the employment of special infantry assault squads (tank fighters).
(2) Experience in fighting Russian tanks at Nomohan, Manchuria, in 1939 gave the Japanese Army an initial warning that more definite provisions must be made in its tactical organization for handling enemy tanks. As a result of much consideration of this problem, which was stimulated by the successful use of tanks by the Germany army in the early days of the present war, a definite plan for resisting tank attacks was adopted. There is every indication that the Japanese have been studying and applying modern pronciples of antitank defense with the same careful attention which they devote to other tactical problems.

b. Exploitation of tank disadvantages.
The Japanese envisage the inherent disadvantages of tank operations to be as given below, and their antitank instruction stresses taking every advantage of these conditions.
(1) Natural and artificial obstacles.
(2) Long tank columns which are difficult to camouflage.
(3) Adverse weather conditions which may prevail.
(4) Unfavorable working conditions and difficult observation which lower efficiency of crews.

c. Tank hunting.
Since the Japanese army teachings lay a pronounced emphasis on coming into close contact with enemy tanks, it is well to draw attention to the fact that tank-hunting tactics are likely to be employed to a greater extent by the Japanese than by other armies. The reason for this is three fold:

(1) It is another manifestation of the Japanese spirit of teh bayonet. The hand-to-hand encounter, in which the individual is expected to triumph over material, even if armed only with grenades;

(2) The Japanese appear to be short of modern antitank guns, and only by denying one front do they produce reasonably strong concentrations on another;

(3) Most of the ground over which they have been fighting lends itself to a close assault.



2. ANTITANK WEAPONS AND ANTITANK UNITS.

a. Weapons. The Japanese army generally has disliked single-purpose weapons.However, this dislike was abandoned from necessity, and early steps were taken to produce a 20-mm automatic antitank rifle which has been found with units in the field. It is carried by four men in combat, and transported on a cart orpacked on one horse if not carried by hand.

Figure 94. Six-gun Heavy (105-mm) Antitank Battery. Note shallow arc pattern with command post in center.
While the 37-mm gun is still retained in service and is issued as a dual-purposeweapon, the 20-mm automatic antitank rifle is believed to be primarily used for antitank purposes. Other field and antiaircraft artillery weapons are considered suitable for use against tanks. A modern 47-mm gun, equipped with a high speed mount, has recently made its appearance. This weapon should have an

Figure 94a. Continued.
effective antitank performance, while its low silhoutte will aid in its concealment.

Nondivisional units. Nondivisional antitank units did not exist in the Japanese army before the Nomonhan incident, but as a result of experiences in fighting Russian tanks, these independent antitank units were formed for attachment to divisions when necessary.

3. PASSIVE DEFENSE MEASURES.
Concealment, camouflage, obstacles, reconnaissance, and warning nets are considered essential.

4. ACTIVE MEASURES.
These include:

a. Action by antitank guns, accompanying guns, and mortars.

b. Bullet splash from machine guns and rifes at short range (at least one squad firing at each tank).

c. Mines .

d. Tank fighters. These comprise men with special training and equipment for direct assault on tanks.

e. Tanks.

5. ANTITANK TACTICS.

a. Mines.
A cheap method of passive defense against tanks is by the use of tank mines. In an exercise involving an infantry division, 12,000 mines were laid by all units of the division. Where enemy units are known to have tanks, the laying of tank mines is considered the most essential duty of the division engineer regiment. The mines are placed in a conventional manner covering the logical route of tank approach.

Bridges in defensive areas are habitually mined, and any bridge which has been in Japanese hands must be carefully examined for the presence of contact mines before a tank unit is allowed to cross. Tank barricades have all possible detours heavily mined, and it is common practice to lay a few mines under temporary barricades with the idea that if the enemy removes the barricade, he will not suspect that mines have been laid in the ground underneath.

b. Tactics

Figure 95. New type of double revetment (Nusa island battery across Wavieng channel), showing detail construction.
A Japanese military term applying to antitank defense is dansei bogyo , which is translated as "an elastic defense" and is highly descriptive of their entire theory of antitank defense. Briefly, this method of combat does not provoide for strong resistance to tank attacks along front lines. Not more tha 20% of available heavy infantry weapons are employed against a tank attack from front-line positions. On the approach of a tank attack all units, with the exception of one squad perplatoon, fall back to positions from 800 to 1,500 yards in the rear.

The squad from each front line platoon left in position scatters widely and, under coverof smoke laid down by the use of the grenade discharger, attacks the tanks with incendiary grenades as they come through the smoke. It is contemplated that this initial stage of the fight will scatter the enemy tanks, rduce control, and cause some casualties.

Figure 95a. Graphical interpretation.
If tanks overcome the resistance of the front-line detachments they come under fire from the main strength of all available weapons of the infantry. While this and the front line combat have been going on, some of the division artillery moves forward to positions from which it can fire with direct laying. If the heavy weapons of the infantry are unable to stop the attack, the main infantry strength, using smoke and incendiary grenades, makes a direct attack, relying on the artillery to their immediate rear to handle any tanks that get through. The main feature of this defense, as stated by provisional regulations, is that once anattack is stopped the enemy is pinched off, and by the operation of scattered units can be destroyed with grenades or any available weapons; and the infantry, although scattered, still can offer successful opposition to enemy infantry attempting to exploit the advance of the tank units.

c. Estimate.
While it may appear that the Japanese army will offer but weak resistance against a tank attack because of the nonavailability of modern weapons in sufficient numbers, This assumption should not lead to the belief that strong and suicidal resistance by individuals will not be offered.

6. DETAILED METHODS OF ATTACKING A TANK.

a. Choice of ground.
When employing tank fighters, it is desirable to choose ground where tanks

must travel slowly and where that attack does not interfere with the action of antitank guns.

b. Special troops.
Each rifle company (sometimes machine gun and heavy weapons companies organize similar detachments) trains certain individuals as tank fighters, and these are specially equipped for such action. Each man is armed with antitank mines and smoke hand grenades.

c. Methods.
Three ways of attacking tanks are:

(1) The tank fighter crawls towards the tank under cover, until he is within dead space of the tank weapons. Next, he throws the mine, attached to a long string, about 15 feet in front of the tank and, by meand of the string, pulls it directly under the tank.

(2) Several pairs of tank fighters move forward under cover and place a number of mines in front of the tank in such a manner that the tank must drive over one of them.

(3) A number of mines are fatened, 1 foot apart, to a 150 foot line. Two mean conceal themselves with this chain of mines and draw the mines across the path of the tank as it approaches.

The tank fighter is also taught to attack the tank by jumping on top, usually from the rear, and damaging the guns or rotating mechanism of the turret with picks. The pistol may be used to fire on the crew through openings in the tank. Another method os tp blind the tank crew by throwing a shelter half over the turret, covering the slits with mud, or "smoking it out". Naturally, all these forms of assault are feasible only if the friendly infantry can neutralize the hostile infantry accompanying the tanks.

Tanks have been delayed and finally stopped, by driving 3 inch wooden poles or 1 to 1 1/2 inch rods between the spokes of its wheels. Magnetized armor piercing mines are also used at times.

7. EMPLOYMENT OF ANTITANK WEAPONS.

a. Allotment. In country that is suitable for the operation of tanks a company of Japanese infantry may be found to be supported by from 2 to 6 antitank guns (37-mm or 47-mm). The infantry regimental antitank guns either may be alloted to forward battalions or, on rare occassions,held in reserve under regimental control. The 20-mm antitank, automatic rifle is described by the Japanese infantry as "delivering antitank fire at short range and engaging the enemy foremost heavy weapons". If there is any danger of a night attack by tanks, the 20-mm weapon may be posted forward of the main lineof resistance and supported by tank hunting detachments.

b. Siting.
The bulk of the antitank guns allotted to a position are sited as far forward as possible. Great stress is laid on siting guns in concealed positions and camouflaging them. To quote from Japanese regulations, "positions are to be selected at well covered points near the front line". Experience has shown that once dug in, these weapons are difficult to locate. It is likely that an antitank gun will sometimes be sitedin very thick cover, with a small fire tunnel cut out to enable it to cover a trail or other likely area for tank approach. The Japanese have sited machine guns in this way, and the practice well may be applied to antitank guns. Guns also may be sited on steep ridges or rocky slopes, from which positions they can fire at hostile

Figure 96. Antitank defense position.
tanks while themselves remaining inaccessible. Alternative positions are prepared, the regulations stressing that "it is advisable to move the gun from place to place thus avoiding casualties from enemy fire". In action the fire unit is generally the individual gun ( a section), and the gun commander shooses suitable targets and directs fire upon them. While most of the guns are sited in foremost defended localities, a few are held in the depth of the position with the apparent task of dealing with penetration of enemy tanks. In the event of such penetration, infantry regimental guns, as well as field artillery weapons, also will engage the hostile armored vehicles.

The fire plan of teh infantry weapons is coordonated with that of the antitank unit. Except for reserves if any all guns are sited to cover the most likely lines of approach of enemy tanks. They are also sited to cover obstacles. An infantry platoon ofetn is disposed on the route of approach in advance of the main position, but within range of artillery support from it. This platoon may have an antitank gun attached to it.

8. EXAMPLES OF POSITIONS.

a. Natural and artificial obstacles combined.

The position illustrated in Figure 96 was prepared by the Japanese near Akyab, Burma. It provides an interesting example of an all around tank obstacle, partly natural and partly constructed. A ditch, approximately 14 feet wide and 7 feet deep was dug as shown. Dirt, thrown out of both sides formed a small parapet, while water filled the ditch. The trench system dug near the ditch included seven

Figure 97. Japanese plan for Antitank defense.
covered positions, each measuring 45 to 30 feet.

b. A plan for antitank defense. In figure 97 there is shown a Japanese plan for antitank defense of an area in Burma. The following troops and guns were alloted to the position:

(1) Area no. 1 was to be garrisoned by 1 company of infantry, reinforced with half of company of heavy machine guns (4 guns), 2 antitank guns, and 4 infantry mountain guns (75-mm).

(2) Area No. 2 was alloted 1 infantry company with half a company of heavy machine guns (4 guns), 5 antitank guns and 4 infantry mountain guns (75-mm).

(3) Area No. 3 was assigned 1 company of infantry, and 2 mountain infantry guns (75-mm),

(4) Area No. 4 was defended by 1 company of infantry, one half of a heavy machine gun company (4 guns), 4 antitank guns and 2 mountain infantry guns (75-mm).

(5) Area No. 5 was allocated 1 platoon of infantry and 1 heavy machine gun platoon (2 guns).

(6) Area No. 6 was assigned 1 platoon of infantry and 4 antitank guns.

Obstacles.

At Butaritari island, Makin Atoll, the Japanese dug deep antitank ditches outside of their main defenses at the tank traps, with winding narrow roads leading into the outer edges (Figure 98).

The crossings were covered from antitank gun pits and machine gun nests. Palm logs served as a tank barricade near on tank trap. (figure 99).

Figure 98. Antitank obstacle.

Figure 99. Antitank obstacle.