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"Documents Dealing with Japanese Warfare" from Intelligence Bulletin, February 1943

[Intelligence Bulletin Cover]  
The following translations of Japanese documents were published in the Intelligence Bulletin, February 1943.

[DISCLAIMER: The following text is taken from the U.S. War Department Intelligence Bulletin publication. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]



All the information given in this section was taken from translations of Japanese documents of various types; most of them were written within the past few months. They deal almost exclusively with warfare in jungle areas. In some instances, the information has been rearranged or paraphrased in order to make it more logical and readable.


After having passed through the enemy lines, and while making a reverse turn in the jungle (attack from the rear), absolute secrecy is still essential to success in attacking the enemy. Each unit will bear this in mind, and will see that each individual soldier clearly understands our plan of attack.

Special precaution must be taken in regard to the following points:

a. Cooking operations must be carefully concealed, both day and night. Cooking must cease at least 1 hour before daybreak, and the fire must be extinguished completely. In going to a river for water or bathing, it is necessary to select the naturally concealed places, or to camouflage a place from enemy air observation.

b. During the approach in thick forest, liaison is made chiefly by telephone and messenger. Prohibit the use of radio. These methods are to be changed only after the attack is started.

c. If the approach is along a road, the road should be wide; if not, remove the weeds near it. However, do not let the changes become visible from the air. Units making a round trip should strictly enforce rules for passing on the left flank, and should prevent delay in the advance.

d. Do not make the forest thin by such action as would damage the large trees near roads and bivouac areas.

e. Progress through clearings and open places in the jungle, must be made swiftly and in an orderly manner. Again, when enemy planes are overhead, the unit is required to stop temporarily, even in a forest, if there is any possibility of being observed.

f. It is necessary to take precautions against talking out loud or shouting, even in the forest, because of native spies, enemy sound detectors, and enemy scouts. This is especially the case when close to the enemy position. Again, if the natives are being sighted, it is necessary to kill them immediately.

g. During the movement of each unit, it is necessary to organize an observation party to carry out strict supervision and observation of this movement and to take various other precautions.

h. The approach-march speed of units in the forest must be the same as that of heavy fire weapons. Include in original plans the sending ahead of time of a supply of ammunition and a 12-day supply of provisions.

i. It is necessary for each unit to secure close control in thick forest, using rest periods to reassemble the main force. Particularly because of soldiers being delayed and falling out of rank, it is necessary for leaders to keep strict supervision.


a. The commanders (accompanying an advancing construction unit), together with engineer personnel, will go to the jump-off position being prepared for the division, and will select and mark the sectors to be occupied by the various units. Especially try to scatter each unit involved in the initial fighting, selecting good camouflaged positions. You must take all precautions against enemy discovery. In case you are discovered and receive shells from the enemy, you must be prepared to take any measures necessary.

b. Then each front-line commander will reconnoiter his terrain in preparation for advancing, will indicate the nature of routes to be taken, and will select the next stopping place (deployment line).

c. Movement of the main division force to the jump-off position must be made one night before the day of attack. It is very important to carry out these instructions without confusion, shortening the day of readiness in front of the enemy as much as possible.

d. Each infantry regiment in the division jump-off position (generally about 3 2/3 miles inside the forest) will make a deployment. Then each battalion in the first line will select a battalion deployment position, temporarily on a line generally about 1 1/2 miles inside the forest. Deploy after advancing to this line on the route which is already constructed, and again prepare for attack.

e. Each company on the first line will naturally have the approach route open up to the time the battalion advances into the jump-off position, and will approach to approximately 1 1/2 miles from the edge of the forest (same as the battalion deployment line) and make a deployment. Then the preparation of the attack will be made. Afterwards, a leader is required to make a reconnaissance before the attack. Hereafter, at dusk, you will advance to the line at the edge of the forest; if necessary, crawl through the jungle zone, and immediately rush on to the enemy position after giving the signal.

As it is best for each flank unit to make a rush at the same time, the time should be regulated. Therefore, consider the distance of the forest line and plan for a simultaneous rush.

f. When approaching the enemy, the possibility of encountering enemy patrol and security units must be taken into consideration. It is necessary to annihilate them, as far as possible, and not make any errors. It is necessary to make plans for immediate annihilation of lookout facilities and microphones of enemy artillery organizations when they are discovered.

g. During an approach to an attack, each commanding officer must take the responsibility for maintaining the direction of advance and make the line of development parallel to the enemy line. Even though there are times when enemy fire is received, it is necessary to control the subordinates and not let the unit become confused.


a. Control of units is the key to successful attack in a dense forest (jungle). When each flank unit makes a rush at the same time, as one group, no matter what the position may be, it can be taken.

b. Flanks of enemy positions can easily be discovered by light tracer bullets. Therefore, every effort should be made to rush from the flanks. It is also very important to assault by immediately chasing the retreating enemy without stopping. When the enemy has observed our assault, he will retreat and concentrate his fire on the point just evacuated. At this time give a part of the unit the previous duty (the assault), and make a suicide attack into the enemy positions, especially at the antitank gun position. Attack the remaining enemy with mopping-up action. It is very important to make a complete annihilation by dawn.

c. The enemy is very fearful of our assault, and each unit has a tendency to gather into groups. Against such an enemy, hand grenades are very effective.

d. The units rushing the area around an airdrome must try to avoid setting equipment on fire or spilling gasoline. Shoot at the rubber tires and not at the engine of a plane.

e. When advancing to an attack through a dense forest, take precautions on open ground as there may be cases when there is a zone of concentrated enemy fire.

f. When a large number of enemy prisoners are taken during the progress of combat and are looked after by small groups of guards, it is best to take away their weapons and remove their shoes.

g. Take measures to prevent attacks on the left, right, front, and rear of the friendly force. Moreover, carry out the signs of the commanding officer and select each ranking officer to carry out controlled leadership, taking precautions to maintain the thrust to the end.


This paragraph consists of tactical opinions given by all officers of a Japanese battalion--after they had experienced considerable combat against United Nations forces in Southwest Pacific islands. A preface to the document stated, "Each unit creates necessary devices, based on these opinions, after considering the enemy combat methods."

a. Marching Through Jungle

(1) Leave some distance between the engineer unit and the units that follow. Moreover, have liaison men advance at least 200 to 525 yards ahead.

(2) The leader at the head must always allow for deviation of compasses.

(3) It is advisable to assemble each unit when resting, as it is customary to march over the road in single column.

(4) Because jungle units carry lights, the commanding officer must advance his unit by leaps and bounds from one defiladed area to another.

(5) The engineer unit must regularly report to the commanding officer in the rear regarding the status of preparations and terrain features at the front.

(6) Camouflage of each individual and each gun must be thorough. Moreover, when crossing a grassy plain, camouflage by using the grass.

(7) If enemy planes are overhead while you are in a grassy area, lie prone in the tall grass and hide the body by placing grass over it with both hands.

(8) Generally, infantry assistance is necessary for heavy weapons units. The minimum is one platoon for a machine gun and one platoon for an infantry battalion gun.

(9) The rate of march for a unit during a day should be about 4 to 6 miles.

(10) It is advantageous to select a route where water supply is possible.

(11) Although it is best to relieve the engineer unit each day, the leading officer in the front should continue his duty.

(12) When bivouacking in the jungle, it is best to begin sleep at 3 o'clock. Cooking must be performed at the last resting place before reaching the bivouac area, which should be, completed before the units arrive. This is safe and also tends to hide the bivouac area, making it difficult of discovery by enemy planes (at least two men from each squad should be sent forward to prepare the area).

(13) Be at ease while cooking. Use "marsh reed" and bamboo to make fires. It is necessary to cook in several places, not just one. Moreover, it is important to be ready to put out fires immediately in case enemy planes should appear.

(14) During this military operation, there was never a time when we were discovered by enemy planes while in the jungle. It is significant that enemy prisoners never move, even at night, when planes fly over.

(15) When in flat country, the commander should be in the center of his unit. When on a hill, he should be at the highest point.

b. Night Attacks

(1) Never be overconfident with aerial photographs, especially those taken before enemy occupation, because he will make changes. Pictures of areas directly to our front are extremely necessary for the execution of the attack, and they should be distributed at least down to the first-line assault company. This is especially necessary when maps are not available.

(2) It is important to have sufficient time to move into a jump-off position for an attack. Going long distances to an assault without eating on the way will only tire personnel.

(3) It is advantageous to use as leaders the fatigue personnel of the navy and the present area guides.

(4) It is very important to consider the effective zone of enemy artillery and mortar fire. If units are rushed into the jump-off position when the enemy artillery is not neutralized, useless damage may result. Only the cadre should advance, and it is ideal to set the time for departure of attack about 10 minutes beforehand.

(5) If artillery fire is not received, it is best to assault without hesitation because heavy losses may result if time is spent in idle complaints.

(6) Most of the fire from enemy positions consists of light tracer bullets. Therefore, the enemy line becomes clear and distinct. It is impossible to attack the front or to assault with a/large force. It is important to send one or two squads around to make an assault on the flank. To make a simultaneous attack, wait for an opportune time and then yell. The noise is very successful in demoralizing the foe.

(7) If a rush is made into the enemy firing line, concentrated enemy artillery fire will always be received; therefore, it is best to rush only when close to the enemy. After penetrating the firing line, engage the scattered enemy soldiers again. Therefore, it is necessary to leave one unit (one squad) behind to carry out the mopping-up work.

(8) It is very important for the cadre and men to immediately cut communication and liaison lines within a position.

(9) There is an inclination for the subordinates to scatter by themselves when concentrated enemy fire is received, and it is necessary to mark the position of the company commander and control the men (subordinates) for a wholehearted assault. Moreover, give the men a positive reason for, and an outline of, the company's conduct of battle. It is also necessary to place in each group someone able to use a compass.

(10) The majority of losses are caused by artillery and by pursuing gun fire. Therefore, when they cannot be neutralized, it is necessary for a plan of suicide occupation. In artillery positions there are many automatic weapons with formidable protection, and other strong establishments.

(11) There are many dead spaces within the enemy position. Give the first-line unit adequate front to investigate the dead space and use this to expand the success of battle from the rear and to the flanks. It is also advantageous to assault. In general we do not investigate dead spaces skillfully.

(12) Complete silence is necessary, since concentrated fire can be received even within a position.

(13) Do not use radios, because fire will be concentrated in their vicinity.

(14) The liaison between regimental and battalion headquarters must be carried out by wire, orderly, and other means.

(15) The control of soldiers' voices and markings for commanding officers is inadequate. Therefore, it is necessary for thought to be given to these matters the day before the attack begins.

(16) To carry on the battle after daybreak, the heavy guns must advance during the night--advancing over long distances after daybreak is impossible. A section of the heavy gun cadre must advance behind the first line, reconnoitering the route of advance, and have the unit in the immediate rear pay strict attention.

(17) The enemy usually fires on our jump-off position all night long. It is necessary to advance to the front of the rear unit during a lull in the firing.


The information in this paragraph was taken from a Japanese bulletin, prepared by a Marine (Naval Landing Party) commander and designed especially for unit commanders of Marine forces. The bulletin apparently was written before the Japanese met severe opposition in the Southwest Pacific Islands.

a. Handling Personnel

Would you throw away the lives of your men, who have been placed in your keeping by the Emperor, by recklessly sending them on a frontal charge in the face of the enemy fire and ignoring your own shortcomings in leadership and strategy? As a commander, bear this well in mind.

In a word, your object must be to attain the greatest results with the smallest sacrifice. If you order your men to advance, they will obey you in any circumstances and at all times. But remember that before doing this, you are to take the minutest precautions. Do not forget to explain to your men, as carefully as if they were little children, how and in what direction to advance, the places to watch, and what to do when shelled or attacked by hand grenades.

For example, how many men would have come through unscathed if they had been ordered to "lie down until your head is on the ground." This may sound like a graceless criticism of men who have given their lives, but I believe many men have become casualties through their own carelessness and want of caution. It is true that we have dedicated our lives to the nation and will not begrudge them at any time, but we want to accomplish something by our death--not die uselessly. We want to die gloriously. We hope for a death worthy of a Samurai... and we owe it to the men under our command to enable them to do likewise. If you do this, as the commanders of a unit, your mind will have a measure of peace.

In maneuvers, we have always had it emphasized that we must get a grasp of actual conditions. During the battle of east Hwatelo (in China) a certain unit commander boasted that he had decided to make a charge, and thereby greatly embarrassed his company commander. I believe this was a case of blind decision. We had been ordered by the battalion commander to strengthen our position and defend it to the death--this meant, if your arms are broken, kick the enemy; if your legs are injured, bite him; if your teeth break, glare him to death. This spirit is expressed in the words "defense to the death." The time to launch a charge is when the enemy has reached the limit of exhaustion, as laid down in the manual. In defense, we believe that if you can hang on to a position with one light machine gun, one platoon can successfully crush the enemy.

The unit commander must not give up hope or make pessimistic statements. In a battle, always remember the "4 to 6 ratio"--if 4 of our men are knocked out, consider that we have got 6 of the enemy. Whatever may be our own losses, strive to keep up morale. The more violent the fighting, the calmer and firmer must be the commander's bearing, orders, and words of command. It is also important, in the interest of morale, not to let the personnel of the unit know the number of killed and wounded, or their names. Heavy enemy shelling also affects morale, and sometimes troops will not fight as they should. The effect is still more marked when there are casualties.

Some young soldiers think it heroic to expose themselves to the enemy. Take care of this, particularly in a battle of positions.

When fighting is protracted, there is a tendency to get accustomed to the enemy, and relax vigilance against enemy fire and hidden enemies. We have been sniped time and again. Pay particular attention to this.

b. Pointers on Close Combat

Too long a halt in the same area will result in drawing concentrated fire from the enemy, and is inadvisable. The proportion of hits from bullets is smaller while you are moving than when you are stationary. In a charge, if you meet concentrated fire from the enemy at close quarters and lie down and stay glued to the same spot, you cannot advance. Also, the longer you halt, the more your will to advance is blunted, and the greater your casualties. Therefore, charges must be made with determination and daring. A daring and determined attack is the key to victory.

In a charge, the platoon commander must be at the head, as indicated in the manual. The charge is the moment when hardship and fatigue reach their climax, from the commander of the unit down to the last man. At this time, if everyone is determined to carry out the unit commander's orders without hesitation, and if the platoon commander advances at the head of his men, the spirit of daring and solidarity aroused in the company will enable them to penetrate the enemy position.

"After victory, tighten your helmet strings" (an old Japanese proverb). After fierce fighting, or during a pause in the battle, the mind is apt to relax. This is the most dangerous moment. Even men who are daring and determined during a charge have a tendency to be cowardly as soon as the fighting changes to mopping-up operations, and only scattered fire and small numbers of enemy troops are encountered.

c. Use of Machine Guns

In a naval landing party (Marines), there is virtually no necessity for a machine-gun company. It is preferable to include in each company a machine-gun platoon under the command of the rifle company commander. From the nature of a naval landing party, there is practically no occasion on which a machine-gun company joins in the action as an independent unit with its six machine guns. As a rule, each platoon is detached, and is organized under the rifle unit company commander. This is particularly true in the case of street fighting and fighting at close quarters. Even if a machine-gun company were independent, it would be difficult for it to put up a vigorous fight without the support of the rifle units. Nowadays machine- gun squad training is the main consideration in machine-gun training, and the need for machine-gun company exercises is not particularly felt.

All machine-gun personnel, with the exception of the gunner, must be armed with rifles. This is especially necessary in street fighting, fighting at close quarters, and so on. Even when attacking and advancing, the carrying of rifles never impedes the advance. In case of an enemy attack, it is easy to make a sortie with the machine-gun ammunition personnel. The ideal rifle for machine-gun personnel is the 1911 model carbine, which is nearly 12 inches shorter than the 38-year type, model 1905.

d. Miscellaneous

The gun loopholes of a position must always be screened with pieces of cloth or matting. If the enemy can see through them, his snipers may fire at them, or he may concentrate his fire on them. This is particularly necessary in the case of openings for heavy machine guns, which must be large on account of the angle of fire.

Even when an action is going on, arms must always receive proper care; otherwise numbers of such arms as rifles, care of which is apt to be neglected, will be found red with rust. It must be impressed upon the men that exchanging fire with the enemy, is not the only battle—taking proper care of arms is a great battle in itself.


This "Outline on Defense" was dated Sept. 1, 1942, and was distributed on at least one Southwest Pacific Island.

Special attention should be given at this period to the following matters concerning defense:

a. Selecting a Position

When selecting a defensive position, bear in mind that the enemy in attacking may not establish an extensive field of fire, but may concentrate fire power in a surprise attack from extremely close range. Special consideration should be given to concealment from the air.

b. Disposition

The enemy will approach through the jungle and may attack from all sides, especially from the rear. As a counter measure, deploy all units, from squads to regiments, in circular formation, changing the original frontal positions as the enemy advances.

Utilize oblique and flanking fire to the fullest effect.

c. Construction

(1) To the extent that time permits, construct strong defensive works, including shelter if possible. (Australian methods are most incorrect.)

(2) Provide positions for grenade dischargers, light machine guns, machine guns, and other appropriate heavy firearms. Depending on the enemy situation, either fire in the anticipated direction or hold your fire to avoid disclosing your positions and inviting destruction.

(3) Various types of obstacles should be constructed within the jungle where they will be least expected by the enemy, thereby affording opportunity to strike the enemy at selected places.

(4) Establish ammunition dumps in locations affording maximum protection from detonation by enemy bombs. When storing large amounts of ammunition, construct dumps in several places.

(5) Endeavor to deceive the enemy by constructing dummy loopholes, dummy soldiers (with steel helmet, knapsacks, and so on), and dummy trenches.

(6) Each squad should look after its own water containers, making full use of empty cans abandoned by the enemy.

d. Various Other Preparations

(1) Use every means to secure as much ammunition as possible. The company in particular should utilize captured weapons to the best advantage (especially automatic rifles, captured ammunition, and hand grenades).

(2) Consider the fire sectors covered by rifles, light machine guns, hand grenades, and so on. Do not omit the preparation of hand grenades.

(3) Allow the enemy to approach very close, then fire calmly at individual targets.

(4) Use ammunition sparingly if it should become scarce.

(5) Do no make a sortie or counterattack heedlessly, simply because the enemy has approached. Such actions may have immediate advantage but casualties will soon result, and it will be difficult to maintain the position. Remain calm as the enemy approaches, and fire to annihilate.

(6) Pay close attention to sanitation, considering the length of time your position will be occupied.

(7) Make certain that adequate provision is made for drainage of quarters, water supply installations, lines of communication, and so on.

(8) In the absence of the enemy, assign one section as lookouts.


a. When Opposed

When opposition is expected, it is best to begin operations before dawn so that occupation is possible at dawn.

Make your landings with the boats in column formation. Or, if the situation demands, use the line formation.

If the landing point is steep, dash under the position so that you will be under the angle of fire.

b. Procedure After Landing

(1) All white troops and police will be captured. In case they resist, they will be killed by shooting and bayoneting.

(3) All white persons and Chinese (including women and children) will be thoroughly searched and all arms confiscated. They will be assembled and confined in a suitable place.

(3) As it is difficult to distinguish Germans and Italians from other whites, they will all be confined together.

(4) Native policemen will be disarmed and confined; however, since they are to be used later for police work, they should be treated with consideration.

(5) In case there are any Japanese, they should be released at once.

(6) Beware of small land mines, especially in the vicinity of the pier.

(7) Do not stupidly drink water or eat anything, as it may be poisoned.

(8) Installations, machinery, goods, and so on will be used later, so do not willfully destroy them.

(9) All radio equipment will be confiscated.

(10) When searching persons, all notes and other written documents must be confiscated, and their contents inspected. The necessary steps will be taken so that at a later time the holder of each document may be identified.

(11) Be especially careful not to destroy furniture, water tanks, ice boxes, safes, and so on.

(12) Cans of food and other useful things should not be punctured with the bayonet in order to inspect them.

(13) It is forbidden to waste food and other material willfully.


Concerning the secrecy of the battle plan, the following items must be understood thoroughly:

a. During the daytime, there should never be any cooking;

b. Absolutely do not expose any bright lights, even though you are handicapped by darkness;

c. Do not throw any fording materials in the river;

d. Do not talk loudly;

e. Since the natives in this area are not trustworthy, soldiers must not discuss troop movements;

f. Do not use native roads;

g. Do not say "Oi Oi" (English equivalent of "hello"), as this shows that one is not well mannered.


a. They do not like the jungle at night;

b. They fear our night attacks, especially our battle cry;

c. They use grenades within their positions;

d. Their artillery uses one "leading" shell out of every five shells;

e. They do not make sorties while in a defensive position, and they respect our fire power.


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