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"Fighting in the Solomon Islands" from Intelligence Bulletin, December 1942

[Intelligence Bulletin Cover]  
The following report on Japanese tactics and weapons in the fighting in the Solomon Islands was originally published in the Intelligence Bulletin, December 1942.

[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.]



The Intelligence Bulletin for November included a section on the early fighting in the Solomon Islands. Since that time additional reports have been received, giving much more information about Japanese tactics and weapons. All the reports are from officers and enlisted men who took part in the operations. In presenting the new information, duplication of data given a month ago is avoided as far as possible.

Our observers are placing renewed emphasis on the extreme cunning, treachery, fanaticism, and brutality practiced by the Japanese. Several instances of these practices are given in this section. It is the belief of our observers that our troops must take nothing for granted in dealing with the Japanese and must ever be alert for any possibility.


a. Reconnaissance

The Japanese are firm believers in securing detailed intelligence about their opponents, and have been very successful to date in this aspect of operations. They have prepared maps of great detail, even of jungle areas. They have had considerable success in radio interception, taking good advantage of the information obtained.

One Marine patrol came upon a 25-man Jap patrol in the Solomons and accounted for at least 18 of the enemy. The Marines reported that the Japanese were exceedingly well equipped. They carried portable radio transmitters and mapping and sketching equipment. Our interpreter read captured messages indicating the presence of a landing force and including other valuable information, which was used by our troops in dealing successfully with the Jap force.

b. Infiltration

Our observers continue to stress the infiltration tactics of the Japanese in jungle warfare. Individual Jap soldiers, with light but very effective equipment for independent combat, crawl through jungles so thick that it would appear impossible for a human being to penetrate. Yet for miles they wriggle their way through on hands and knees, or on their stomachs--taking several days, if necessary. Once behind our lines or on our flanks, they often get together and form large and effective patrols, which cut off or wipe out our outposts. They seek to weaken our main positions and make us vulnerable to an attack in force.' Often these infiltrating groups, which include snipers, are assisted by covering fire from heavy machine guns, automatic rifles, and mortars.

At night, the infiltration tactics apparently are aimed at creating confusion in our ranks and destroying our automatic weapons. (This bears out the importance of our training doctrine which calls for riflemen to protect our automatics from the front, flanks, and rear.) At times Jap groups tried to stampede our troops, shouting "American Marines, you die!"--which apparently is a battle cry. Sometimes these groups were so small that their members must have realized that they were attempting a suicide venture. On one occasion, a Japanese lieutenant and two privates charged a Marine battalion headquarters, shouting their battle cry. One of them bayoneted a Marine sergeant as he sat on a stump. The three were immediately overpowered and killed—they must have known in advance that the charge would lead to their death.

c. Sniping

In many respects snipers caused the Marines more trouble than any other single factor. Sniping is tied up very closely with offensive infiltration attacks, and also with nearly all the defensive efforts of the Japanese. Normally, the snipers tied themselves in the tops of trees, where they were well camouflaged. Often, however, they were found in nearly every place where they could hide--such as behind logs and in bushes, caves, or ravines. At night, several Japs leapt into foxholes occupied by Marines and were killed because they could not give the password.

Usually the snipers waited until their target had passed and then shot him in the back. They seldom fire on individuals in movement. This is why our troops now take cover at once when they halt.

The main function of the snipers apparently is to harass and confuse our forces, distracting them from their main effort. "Our troops found it most undesirable to allow the assault echelon to become involved with snipers on the flanks and rear," said one observer. "In a number of instances, it was found practicable to bypass the snipers with the assault echelon and let small follow-up patrols clean them out later."

After shooting snipers who had tied themselves in trees, our troops had trouble in getting the bodies down. The problem was solved by having a tank knock the tree down, or by placing a ring of dynamite around the base of the tree and blowing it up.

Japanese prisoners said that normally each of their infantry squads included two snipers, who ordinarily tied themselves to tree tops in the area occupied by the squad.

Nearly all conceivable types of camouflage have been used by these snipers. Some in the Solomons wore fiber cloaks, which blended perfectly with the coconut tree trunks.

The snipers, as well as other Jap troops, have unbelievable patience and endurance. The Marines had numerous cases where their enemies crouched or lay in one position, highly camouflaged, for as long as 3 days just to fire one shot--undoubtedly realizing that they would be killed immediately afterwards. As an illustration, one of our men at Milne Bay (New Guinea) relates the following:

"A Jap, camouflaged as a tropical bush, crouched for 2 days without moving, on the edge of an Australian jungle outpost, to learn the names and nicknames of members of their detachment and their particular habits. One day, in a perfect Australian accent, he called out, "Say, Bill, where are you? This is Alf." When Bill shouted in reply, the tropical bush suddenly arose and shot him dead. The bush immediately dropped back into the foliage. The sniper was wounded only after the area had been completely raked by machine-gun fire. The Jap, wounded severely, told his story. He had fully expected to die after the shooting."

d. Communication

The Japs have been using for communication a large number of very efficient, light-weight, and portable radio transmitters and receivers, as well as flares, Rising Sun flags, and bird calls.

Red and white flares, as a rule, have been used to outline their front line and also to signal the arrival of a unit on our flanks. The flares have been extremely useful to our forces, who have successfully raked the areas with artillery fire.

Rising Sun flags have been tied to trees to inform Jap aviators of the front-line positions of their troops. The flags also proved to be valuable aids to our aviators, who bombed the indicated areas with excellent results.

The bird calls apparently were used as a night signal to inform commanders as to the whereabouts of their various sub-units. Sometimes the calls also may have been used to confuse our troops.

e. Antitank

Antitank weapons used by the Japanese include what is believed to be a 47-mm gun, grenades, and gasoline. At times, when our infantry was not within supporting distance of our tanks, gasoline was thrown on the latter and set on fire. In at least one case, the Japs jammed a driving sprocket before throwing on the gasoline.

Grenades apparently are thrown at the tanks to set them on fire after gasoline has been thrown on them, and to hit openings through which the crews can be injured.

It is known that the Japanese have been trained to throw shelter halves over the slits of tanks in close country and then attack them with magnetic bombs or other hand weapons.

The antitank gun made a hole slightly larger than our 37-mm shell, and observers are reasonably sure that the weapon is a 47-mm gun. This is entirely probable since the Germans have a 47-mm antitank weapon. One shell, apparently fired from a distance of 100 yards, penetrated the right forward side of an M-3 turret and hit the opposite turret wall, where it exploded. Filling from the shell ran down the wall and began to burn with a yellow flame and bluish smoke. The driver stated that fumes from the substance were sharp and stifling, and caused his mouth to dry and pucker. The flame was difficult to extinguish. Reports do not indicate whether the tank hit was a light or medium M-3; but at a range of 100 yards the turret of a light M-3 could be penetrated and it is possible that a medium tank turret could be penetrated at this range.

To date, there has been no evidence that the Japanese actually have used magnetic tank grenades in the Solomons, although some of these grenades have been captured on Guadalcanal.

f. Deception

The Japanese go to extremes in the employment of deception. Many of these illustrate their treachery and lack of scruples. The following is a partial list of the deceptions used in the Solomons:

(1) While an American doctor was dressing the wounded leg of a Japanese, the Jap pulled a knife and stabbed him.

(2) Several Japanese nurses walked up to our wounded with their arms raised, and, when close at hand, they threw hand grenades among the soldiers.

(3) Two or three days after the Marines landed in the Solomons, a Japanese captain of a labor battalion walked into a division headquarters and surrendered. He said his entire battalion would surrender and could be brought in if a detail were sent out to their position, which was some distance down the beach. A colonel and a detachment of 20 Marines were sent in a landing boat to the specified position. As he and the detachment stepped ashore, they all were killed except a sergeant, who was wounded. He returned to headquarters. A Marine force rounded up the Japs shortly afterwards by attacking from the rear. Instead of being a labor battalion, the Japanese turned out to be a special-weapons detachment, 200 strong.

(4) Japanese-employed natives often informed our headquarters they had groups of wounded Marines, and offered to guide our rescue forces to the men. We learned from bitter experience that these were Japanese ambushes.

(5) The Japs learned the names of some of our officers, and, during darkness, would call out to them in excellent English in order to locate them, or to issue withdrawal orders to them in English.

(6) They also used the old trick of setting off firecrackers to distract our troops, and to give the impression they were being attacked by large forces.

(7) Among their tricks, the Japanese painted with red crosses all the buildings they occupied, believing that our forces would not bomb the marked buildings because of our high ethics. One such building, when bombed, turned out to be an ammunition dump.

(8) On one of the small islands taken in the Solomons, the Marines ran into some tough fortified opposition and called for 1,000-pound demolition bombs. The group air commander of an aircraft carrier was directed to bomb the island, and, on his way to the island, he received a counter-order stating that the Marines had now gained possession of the island and that he was not to drop any bombs. "Authenticators" (pass words) had been worked out among the pilots the night before, using the pilot's nickname. The voice countermanding the order was unable to furnish the correct authenticator and the bombing was carried out. The commander discovered that the voice on the radio was that of a Jap, who was speaking English and using a perfect American accent.

g. Camouflage

Instead of using sandbags as part of their defensive setups, the Japanese used bags made from rice straw and filled with dirt. Apparently, unhulled rice seeds or seeds of a similar plant were planted on the top portion of the sacks, because they were covered with a green growth. This blended the defensive positions with their background.

The Marines found from experience that our grenades and mortar shells should be painted green. When they are painted a light color, they can be seen easily at night. In several instances, the Japanese were able to pick up the grenades in the darkness and throw them back before they exploded. Our troops are finding it best to remember that the time delay of our grenades is between 4 and 5 seconds, and that the length of time the grenade is held by the thrower should be governed by the distance between him and the enemy. It should never be held more than 2 seconds.

h. Night Operations

Japanese troops are particularly well trained in night operations, and they prefer night attacks to those during daylight. Invariably, they try to work small groups to our flanks and rear in an attempt to cause panic and destroy automatic weapons.

In making night attacks, the Japanese select clearly defined terrain features, such as ridges and streams, for successive objectives. The attacks generally are delivered on a narrow front and uphill whenever possible. By attacking from low ground, the Japs try to conceal their forces and at the same time silhouette ours against the sky line.

A series of red flares (similar to our Roman candles) have been used by the Japanese platoon leaders to indicate the direction of advance. The signal for the assault has been a flare fired to hang over their objective.

In several instances, they placed smoke on Marine positions and then charged forward, shouting "Gas!" in English. Some Japs who had infiltrated to our flanks and rear shouted "Withdraw!" when the frontal attack began to develop in force. The groups that were to make the main assault talked and sang during their approach, to distract our attention and facilitate and cover the movement into position of the infiltration groups.

The Japanese used their automatic weapons extensively at night, but did very little firing with rifles. In attacking, their fire usually was high, apparently to avoid hitting Japs who approached our lines to lay down grenade barrages. An assault generally followed each barrage.

Our automatic weapons, mortars, and artillery were excellent in breaking up night attacks.

i. Defense

Against our landings on the various islands, the Japanese used mostly rifle and machine-gun fire from dugouts and other prepared emplacements, supported by the inevitable snipers. Our preparatory bombing and shellfire had caused few casualties, because the dugouts, shelters, and trenches afforded the Japs excellent cover. The preparatory fire kept the enemy under cover while our first and second waves landed. The fighting developed into a series of attacks on dugouts and the destruction of snipers in trees. Use of improvised flame throwers and dynamite at dugout entrances proved the most effective way of dealing with the defenders.

j. Air

(1) Fighter planes.--Japanese fighters come in from all angles when attacking our bombers. The Japs press their attacks furiously when our bomb-bay doors are opened for a bombing run, approaching individually from many angles but attacking at the same time.

(2) Bomber planes.--The bombers used by the Japs are of a twin-engined type similar to our B-26. They usually bomb from about 25,000 feet.

(3) Antiaircraft fire.--Antiaircraft fire from Japanese ships is usually inaccurate except from battleships and heavy cruisers. All ships fire a barrage overhead when our bombers are making runs over them.

(4) Direction Finders.--The Japanese are now using radio direction-finding equipment in the Solomons to detect the approach of aircraft. Their equipment has not been very effective to date. Antiaircraft guns sometimes do not fire until our bombers have made their first run, and sometimes our bombers arrive over the target before the Jap fighters are able to take off.

(5) Identifications.--Observers feel that training in the identification of aircraft (and also of ships) cannot be overemphasized. They believe that actual service in the combat area is necessary to perfect this training.

k. Prisoners

The Japs seldom retreat or surrender. All those captured invariably ask, "When are we going to be killed?" Upon learning that they are not going to be killed, they beg never to be exchanged and sent back to Japan. They believe that it is a national disgrace for them to surrender, and that they and their families would be shunned for the rest of their lives in Japan.

The Japanese attitude toward surrender was illustrated in an incident that occurred during the first day of the operations in the Solomons. Five crewmen of a Jap bomber, shot down over Tulagi harbor, got into the plane's rubber boat but refused to be rescued. A U.S. destroyer approached, but one of the boat crew with a gun held off the rescuers. When it was apparent that the Japs were going to be captured by force, the man with the gun killed his companions and was turning the gun on himself when he was killed by machine-gun fire from the destroyer.

l. Food

Even in swamps and jungles, the Japs have learned to live off the land. Usually they are sent on missions with an emergency ration which includes rice and compressed and condensed foods, such as dried fish and vitamin tablets. They supplement this with jungle food that our forces generally would not consider eating. They are experts at knowing what is good for them, and what is poisonous or not good to eat.

m. Medical Care

The Japanese appear to have thorough knowledge of tropical diseases. They also know what poisonous bites to expect, and how to treat them. They seem to have some antitoxins, against jungle diseases, that we have not developed.

Most of the wounds our forces received in the Solomons were not serious. Unless a vital spot is hit, the Japanese 25-caliber weapons do not inflict bad wounds.


a. Rifles

The Japanese have used two types of rifles, one of 6.5-mm caliber and the other of 7.7-mm caliber. The 6.5-mm rifle apparently has no telescopic sight; however, the sight has an attachment for leading planes during antiaircraft fire. The attachment can be adjusted to the speed of the plane.

b. Grenades

Japanese grenades are smaller than ours, and their effective bursting radius is much smaller. The Japs apparently realize the ineffectiveness of their grenades, because they throw them at their opponents and promptly charge with bayonets.

c. Mortars

The Japanese are using two or three types of mortars, one of which is reputed to be fired from the thigh of the gunner when he has assumed a squatting position. Later reports, however, indicate that the weapon is fired only while resting on the ground in front of the gunner.

d. Guns

These include a 47-mm antitank gun and a 77-mm gun. The latter is believed to have been captured from the British on Singapore Island. It is not known to be an organic part of Japanese artillery. (This 77-mm gun undoubtedly is either a 75-mm or a British 3-inch gun.)


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