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"Combined Attu Reports on Japanese Warfare" from Intelligence Bulletin, October 1943

[October 1943 Intelligence Bulletin Cover]  
The following is a report on Japanese tactics during the WWII operations on Attu Island from the October 1943 issue of the U.S. Intelligence Bulletin.

[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.]



This section has been compiled from various intelligence reports submitted by U.S. observers during the operations on Attu Island. A preliminary report on the Attu operations was published in Intelligence Bulletin, Volume I, No. 11. Except for isolated instances, none of the information in the preliminary report is repeated below.


With few exceptions, the individual Japanese soldier on Attu lived up to all our expectations. He was tough, active, tricky, and treacherous, but absolutely no "superman." He was subject to fear, to confusion, and to thoughtless acts of desperation. As a rule, however, he could be counted on to fight to the last....

Regarding the characteristics of the individual Japanese soldier, a U.S. platoon leader says:

I feel very definitely that if a continual advance is made on the Jap, he becomes confused and doesn't quite know what to do next. One thing is certain. This business about his being a superman is so much tripe. When you start giving him the real business, he will run like hell and be twice as scared as you are—and when I think how scared I was, that's saying a lot.


a. General

As a rule, the Japanese on Attu organized their defensive positions on high ground which ordinarily (1) afforded plunging fire on the flanks and rear of forces pushing inland from the coast, (2) was extremely to moderately hard to reach, (3) was largely secure from our naval fire and aerial strafing, and (4) was extremely hard to observe from the valley lowlands.

The enemy apparently organized the terrain so that they could obtain the best possible performance from each rifle and automatic weapon. Positions frequently were located high in side gullies. Trenches or tunnels (sometimes both) usually connected foxholes, rifle bays, and automatic-weapon positions, so that a single rifleman or automatic weapon man might have several fields of fire and several positions. These enabled the Japanese to take up a new position when, or before, an occupied position became untenable. Such shifting about tended to deceive our troops with respect to the enemy's strength.

The foxholes, trenches, and bays commanding the flanks and rear of inward-pushing forces were far more numerous than the positions set up for frontal defense. Trenches, of the zigzag type, usually were about 75 yards long, 3 feet wide, and 4 to 5 feet deep.

Broadly speaking, the Japanese did not organize a series of strong points, as we conceive it, but organized the terrain into scattered and frequently isolated strong points which were very loosely tied together with supporting fires. In selecting these strong points, the enemy apparently paid little attention to routes for withdrawals. This was particularly true in the case of machine-gun positions.

Sometimes holes which, at a distance, appeared to be foxholes turned out to be entrances to large dugouts, living quarters, caches for supplies, or tunnels to observation posts or machine-gun positions. In several instances, trenches covered overhead with timber, dirt, and other forms of camouflage were constructed so as to connect buildings with gun emplacements.

In many cases small prepared positions for riflemen and machine gunners were found near large rocks, under the walls of cliffs, and in other naturally protected areas.

b. Machine Guns

As a rule, the Japanese emplacement of machine guns was good with respect to mutual support. The guns were seldom placed alone. Each was supported by at least one other gun, generally located from 200 to 500 yards away. This made their reduction more difficult as all the weapons had to be taken at once—otherwise, the first gun position taken would receive prompt support from other positions. In at least one instance, this support was strengthened by the addition of a rapid-fire cannon, which twice forced our troops to withdraw under fire after they had taken a machine-gun position. Also, grenade dischargers were frequently located near machine guns.

Often machine-gun positions were constructed either of blocks of tundra—which offered good concealment but poor protection—or of small and medium-sized rocks piled upon each other. Such positions along the rocky ridge tops afforded good camouflage but, once discovered, were deadly to the occupants because of rock fragments. Several Japanese bodies in these positions showed evidence that flying pieces of rock had caused deaths.

c. Sniper and Observation Posts

Sniper and observation posts were well located with respect to the terrain. They had no paths leading to them, and were well camouflaged with grass and, in some instances, turf and moss. A few of these posts had a T-shaped stick, about 3 feet high, which apparently was used as a rest for field glasses. The Japanese sniper or sentry apparently approached his post from a different direction each time he reported. Relief parties did not come close to the post.


a. General

By siting their weapons on high ground, the Japanese secured maximum fields of fire and excellent opportunities for long-range fire. They utilized both advantages. Most of their fire came at us from ranges of 1,000 yards or more. Some of the enemy's heavy machine guns were equipped with telescopic sights for long ranges, up to 2,500 yards.

This long-distance fire, delivered from high, well-concealed positions, was plunging steeply when it reached our troops, and frequently pinned them down. Except for its harassing value, this fire was not considered effective. The enemy's rifles and machine guns had no grazing fire at such long ranges, and the cones of fire were too dispersed to be effective against individuals. Also, the opening of fire at such long ranges gave our forces a pretty good idea as to the location of the Japanese positions.

b. Machine Guns

In addition to siting their machine guns well, the Japanese also had prepared elaborate range cards for firing. Apparently many of the guns had been registered carefully on terrain features before our troops went ashore, and had been laid on specific ground areas with planned patterns of mutually supporting cross fire. In many cases the enemy guns on ridges were set to search out every hollow in certain valley areas. Small range and deflection stakes were often found in front of enemy positions. This arrangement permitted the Japanese to open well-aimed fire, regardless of visibility.

As our troops advanced close to the Japanese positions, the hostile fire frequently was high—probably because many of the enemy gunners forgot to change their sights.

c. Use of Bayonets

Despite the fact that the Japanese place considerable emphasis on the use of cold steel in training, on Attu the enemy gave a poor performance with the bayonet, as a rule. Some observers believed the enemy may have feared our generally larger stature and, presumably, greater physical strength.

d. Communication

The Japanese placed great emphasis on the disruption of our communication facilities. Our soldiers could traverse wide areas known to be infested by enemy snipers, without being fired upon. However, when a soldier stopped for the apparent purpose of repairing telephone wire, snipers' bullets would begin to whine all around him. In the final all-out enemy attack, bayonets severed our wires in certain areas at an average interval of 20 feet, and rearward communications were disrupted. In some cases, enemy bayonets scratched the insulation off our wires in order to ground the circuits.


a. General

Japanese camouflage on Attu was excellent. The enemy relied mainly on natural material, such as grass, moss, and limbs of dwarf pussy willow trees. Other materials included the usual camouflage nets for the body and head, camouflage capes, strips of rice-straw matting and grass matting, rope matting, dummy men and guns, and white snow parkas (some observers reported that white wrap-around snow pants also were used).

b. Natural Material

Individual hillside positions for Japanese soldiers were usually shielded by pussy willow branches. These were draped with moss and tufts of grass which almost completely hid the opening.

Tufts of grass were used to mask the narrow slits (for observation and firing) of covered positions. The outlines and shadows of these positions were broken up by tufts of grass which were loosely twisted into ropes. Sometimes rice straw was used in making the ropes. Straw matting also was used, to cover openings or excavations.

All of these types of camouflage were generally used on one-man structures, while the principles of limiting shadows and of reducing silhouette elevation to a minimum were also generally well utilized.

c. Rope

Rope 1/2 inch in diameter was found in large quantities. In utilizing it for camouflage, the Japanese opened the rope strands—as in splicing—placed tufts of compressed grass between the strands, fluffed them out, and then twisted the strands of rope back into place. The tufts of grass were 15 to 18 inches long and 1 inch in diameter.

After camouflaging a rope in the above manner, the Japanese coiled it up, or put it into immediate use by tossing a coil over the object to be camouflaged. This and other coils were then crisscrossed and secured until the camouflage operation had been completed.

d. Wearing Apparel

The individual camouflage nets were made of vari-colored netting. Wisps of similarly dyed raffia (strong fibrous strands from the leaf stalks of raffia palm trees) were tied into the string meshes of each section.

Individual nets frequently were laced together to cover conical tents. In many instances high revetments were built around the tents, and the camouflage nets fell at a gentle angle from the peak of the tent to the revetment wall. The practice of locating tents at the bottom of deep and almost inaccessible ravines provided an additional safeguard.

The white snow parkas were used for wearing above the snow line. Where possible, the enemy avoided travel across snow patches during the day unless clad in white clothing. When the enemy soldiers moved across the pale grass of the hillsides they often moved in a crouching position with strips of grass matting held in front of them.

Individual enemy riflemen and observers were supplied with hooded camouflage capes, which were made of light, rain-repellant tan paper. The capes were about 9 by 6 feet, and were tied with tie strings. Behind and under these capes, riflemen and observers could sit for a day at a time, dry and protected from wind and rain and indistinguishable from the tundra.

e. Installations

As a rule, the Japanese constructed cooking and storage chambers, latrines, and bath houses by cutting into the sides of hills or banks. They made these structures blend with the surrounding terrain by grass covers, grass or straw, willow branches, and sometimes turf.

Office buildings, barracks, officers' quarters, radio installations, and hospitals in the more developed centers were generally constructed with only the roof extending above ground level (barabara type). The roofs had low peaks, casting only small shadows. The tops of these roofs were covered with sod, which formed a green carpet over each gable. The sod also helped to shed the rain, and gave limited protection from fragments of shells bursting nearby. Glass windows inserted near the gables as skylights were covered on top with loosely strewn grass to prevent daytime detection, while blackout curtains covered the windows at night.

The Japanese went some distance from the building to dig up sod for covering the roofs. The denuded areas left after the sod was removed were rectangular. It is believed that the enemy prepared the areas in this manner with the belief that the contrasting color would befuddle our air observers.

Similar deceptive techniques were used in outlining entire trench systems, where only the surface sod was removed to reveal the dark earth.

Foxholes and machine-gun nests dug in snow-covered ground were covered with white cloths which blended perfectly with the snow.

Frequently small mounds of dirt were built in front of foxholes and covered with tundra. This made it impossible to see the foxholes from a lower elevation.

f. Dummy Emplacements

Islands at the entrance to Chicagof harbor contained complete dummy emplacements, including wooden guns and straw men (made by stuffing salvage uniforms with dry grass).


Several Japanese "barrage" mortars, a comparatively new weapon, were captured on Attu. The mortar previously had been reported in the South Pacific theater. It was also noted on Attu that the enemy has made slight changes in hand grenades and the Model 89 grenade discharger.

a. "Barrage" Mortar

(1) Description.—The "barrage" mortar (see fig. 6) is a simply designed weapon for area bombardment. It consists of a smooth-bore tube, approximately 70-mm in diameter and 4 feet long; a base plate, a rectangular wooden block, and an iron rod, which holds the mortar in an upright position and controls the angle of elevation for firing. The wooden block, 12 inches long, 10 inches wide, and 8 inches thick, is used to absorb the shock during firing and to prevent the base plate from digging into the ground. The base plate is fastened to the block by two bolts. The iron rod, about 1 inch in diameter and 18 inches long, is fastened to the bottom of the block and extends straight down.

The elevation or depression of the mortar is determined solely by the angle at which the rod is stuck into the ground. The weapon apparently has no range-control device.

The tube of the mortar screws onto the base plate, which has a threaded male fitting. The firing pin protrudes upward from the center of this base fitting.

[Figure 6. Japanese Barrage Mortar.]
Figure 6.—Japanese "Barrage" Mortar.

The shell used in the mortar has an over-all length of 10 3/4 inches and a diameter of 2 3/4 inches (see fig. 7). It is made of steel, is cylindrical in shape, and is painted black. The nose of the shell is capped by a rounded wooden disk on a metal base, and is secured to the casing by six rivets. A red band is painted around the shell just below a wooden cap.

The shell is divided into three main sections, namely:

(a) Base section, which houses a central percussion cap and explosive charges (in silk bags) for propelling the shell from the mortar;

(b) Central section, which houses powder delay trains and secondary charges of black powder for expelling seven bomb containers; and

[Figure 7. Shell for Japanese Barrage Mortar.]
Figure 7.—Shell for Japanese "Barrage" Mortar. (Part a shows the details of the bomb; part b illustrates the three phases of action which occur in the air after the mortar is fired; and c is a view of the shell as a whole.)

(c) Top section, which carries a silk parachute 12 inches in diameter and the seven bomb containers. (The parachute is fastened to a 6-foot-long cord, the other end of which is secured to the inside bottom of the casing.)

Each of the bomb containers, which are made of steel, has a 4 1/2-inch square silk parachute fitted neatly into it. Also housed in each container is a steel tube bomb 3 1/4 inches long and 11/16 inch in diameter. The tube is filled with explosive, and is covered at the open end by a screw cap, which has a hole in its center for the passage of a cord fitted with a phosphorus igniter. The cord is 6 feet long. Its free end is attached to a rice-paper parachute which is 15 inches in diameter.

The seven bombs are marked similar to the mortar shell—they are painted black except for a red band below the screw cap. The bombs also bear the Japanese inscription "Dangerous—don't touch."

(2) Operation.—When the shell is dropped into the mortar tube, its primer falls against the firing pin and activates the propelling charge. In addition to shooting the shell from the tube, the explosion of the propelling charge also fires a delay powder train.

This delay train burns momentarily until it reaches powder charges, the explosion of which expels, in mid-air, the seven bomb containers and the silk parachute housed in the top section. This parachute apparently is designed to check the speed of the shell and throw it violently off its course, so that the bomb containers, with their small silk parachutes, may be scattered without tangling up.

The explosion of the charges that expel the bomb containers also activates powder delay trains in each of the bomb containers. These burning delay trains then explode expelling charges in the base of each container and force the bombs, each with its rice-paper parachute, from their containers. In the case of each bomb, the jerk caused by the opening of its parachute activates the phosphorus igniter which, in turn, causes the bomb to detonate.

Figure 7b illustrates three phases which are involved in the firing of this mortar shell. Summing up, it will be noted that, after activation of the expelling charges in the bomb containers, there are—at least momentarily—15 different elements air-borne by parachutes, namely: the shell casing, the seven bomb containers, and the seven bombs.

(3) Purpose.—The explosive content in the bombs is believed capable of producing a heavy detonation which would shatter the light casing into small fragments—too small to have any antipersonnel effect unless the bombs detonated close to personnel.

The warning inscribed on the bomb suggests that it may also be designed for use as a booby trap. In this case, the blast effect would be highly dangerous.

If necessary to handle an unexploded bomb, the following safety precautions should be observed:

(a) Do not lift the bomb without lifting the parachute at the same time, or vice versa.

(b) Unscrew the cap only when the cord is slack.

(c) Dispose of the phosphorus match composition by placing it in water or by burning it after separation from the bomb.

b. Hand Grenades

The hand grenades inspected on Attu have an additional safety feature. The new safety is a small, loosely set screw which fits into the fuze at the top—underneath the cap. To arm the grenades found on Attu, it was necessary to turn the screw about 180°.

Strewn about most of the captured Japanese positions were a number of hand grenades with their pins pulled out. Since the pins have to be withdrawn and the grenade hit sharply on a hard object before it will explode, the enemy may have removed the pins in order to have the weapons in a better state of readiness. Also, the pins may have been removed so that the grenades could serve as booby traps. In this case, the Japanese probably hoped that unwary U.S. soldiers would stumble onto the grenades, and accidentally kick the fuzes with enough force to cause detonation of the weapons.

c. Grenade Dischargers

The Model 89 grenade dischargers examined on Attu had a small bubble leveling device attached to the right side of the breech. The device indicates the angle at which the discharger is held, and thus enables the operator, or operators, to maintain a constant angle of fire.

The projectile used in this grenade penetrates fairly deep into soft ground before the fuze, which has a slight delay element, is activated. This delay considerably restricted the effective bursting area of the shell.


a. For the Individual Soldier

(1) Packs.—Apparently the Japanese use their standard pack in all climates. It is only slightly larger than the U.S. canvas field bag, and will probably hold only rations, a change of socks, and perhaps a change of underwear. However, the pack is designed so that other articles may be strapped on. Several packs found ready for carrying had a blanket and wool overcoat in separate horseshoe-shape rolls, an extra pair of shoes, a shelter half, poles and pins, and felt leggings. As a whole it was a fairly comfortable pack.

(2) Shelter Half.—The Japanese shelter half is a light-weight tarpaulin about 4 1/2 feet square. It is sometimes pitched like our own, with another to form a pup tent. The halves have no buttons; they are laced together. The pup tent is open at both ends. A segmented, or foldable, pole is supplied with each shelter half. Usually Japanese soldiers simply cover themselves in a foxhole with their own shelter half.

(3) Cartridge Pouch.—The Japanese cartridge pouch is made of laminated duck, which has been thoroughly impregnated with rubber to give it a certain amount of rigidity and yet allow for resilience. The arrangement used to effect a snap closure is simply a buttonhole over a collar-button type steel fastener. The pouch has a partition in the inside to allow for separation of ammunition clips. Loops permit the pouch to hang from the waist belt.

(4) Entrenching Shovel.—The Japanese entrenching shovel has a sturdier handle and a more pointed blade than ours, and it was better for cutting the matted grass roots in the Attu tundra.

(5) Skis.—These were called "Glacier skis." They were short and broad, with about two-thirds of the length extending in front of the toes. This permitted excellent maneuverability and provided ample flotation on the granular-type snow found in the Western Aleutians.

(6) First-Aid Packet.—All Japanese soldiers are taught first aid, and all carry a first-aid packet somewhat similar to the U.S. packet. The enemy has a powder which is designed to serve about the same purposes as our sulfa drugs, and another powder, which the solder takes internally when wounded.

b. Wearing Apparel

(1) Headgear.—Enemy troops on Attu were equipped with a steel helmet, which was painted olive drab and bore the Japanese Army star insignia in the front center. The helmet, somewhat smaller than ours, apparently was made of unalloyed, or poorly alloyed, steel, and it was not as tough or as resistant to shock as the U.S. helmet.

The typical peaked Japanese field cap was found in large quantities. Also found were large numbers of a winter cap, which had ear flaps, and a fold-down section to cover the head, helmet-wise, and also the lower part of the face. The cap was lined with real fur or manufactured fleece.

Also found were grayish purple knitted helmets, made of wool and silk, which could be worn under the steel helmet.

(2) Uniforms.—Japanese officers wore clothing scarcely different from that of the enlisted man. The material for officers' uniforms was superior in some cases, but the tailoring was the same.


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