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"Some Jap Methods of Overcoming Obstacles" from Intelligence Bulletin, April 1944

[Intelligence Bulletin Cover]  
The following U.S. military report on Japanese methods of overcoming defensive obstacles is taken from the April 1944 issue of the 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.]



The following information on Japanese methods of overcoming obstacles was extracted from an enemy publication dealing with field fortifications. A study of these methods should prove helpful to U.S. military personnel concerned with the defense of obstacles against Japanese attacks. However, these methods should not necessarily be construed as complete and up-to-date enemy tactical doctrine on the subject.

In connection with this section, reference should be made to "Notes on How Japanese Attack Pillboxes" (Intelligence Bulletin, Vol. I, No. 12, pp. 54-60).


In determining where a breach will be made in a hostile wire obstacle, select a section which will facilitate the operations, provided the selection will fit in with the over-all tactical plan. Generally speaking, select portions of wire obstacles which have been damaged by shells or bombs, or are easily approached.

The organization and equipment of demolition parties vary according to the particular situation. Personnel include the party commander, operators, and relief men, who constitute a reserve and act as sentinels. The equipment includes wire cutters, Bangalore torpedoes, hand grenades, smoke pots, and, depending on the situation, portable shields, sandbags, and so forth.

a. Operating with Secrecy

To make a breach in a hostile [U.S.] wire obstacle secretly, the demolition party must be thoroughly rehearsed beforehand in all details.

In cutting wires, first investigate the presence or absence of thin wire, the condition of intersecting wires, the presence or absence of alarm installations, and so forth. Then open wide the handles of the wire cutter, raise the catch claw (a stick in a piece of bamboo), and, after slowly inserting the wire cutter all the way at a right angle about 1 foot from a post, press the handles with both hands and make a notch in the wire. Grasp the notched wire with both hands, one on either side of the notch, and hold the long strand fast; without making any noise, bend and break the short strand. Bend the end of the short strand close to the post in the direction of the opposing forces, and immediately thereafter stick the end of the long strand into the ground as far as possible from its point of attachment, or tie it to some natural object.

When two men operate jointly, one man (A) holds both sides at the cutting point, and the other (B) makes the notch. (A) breaks the wire, following the principles outlined above, and (A) takes care of the long strand and (B) the short strand.

While cutting wire, the operator must rest one elbow against his body, on the ground, or on a post. In cutting the lower strands, he will kneel or lie down; he will assume any convenient posture while cutting the higher strands.

In placing Bangalore torpedoes under wire obstacles, two men are employed. After the rear man has removed the safety catch and screwed in the igniter, and the front man has ascertained the spot where the torpedo will be placed, the two operators push the weapon on the ground to its final position. Sometimes a torpedo is placed in position by use of pulleys.

In igniting Bangalore torpedoes, the rear operator pulls the string with a sharp jerk and, within the delay time, withdraws 10 or more yards to the rear and lies down. To avoid any danger, all personnel take full advantage of terrain or natural objects which afford protection.

In case a Bangalore torpedo fails to explode, the demolition party should have a torpedo in reserve, or be prepared to use wire cutters.

Should the demolition party be illuminated by hostile searchlights or receive fire, it must try to maintain as much secrecy as possible and continue its work with perseverance and fortitude.

When the demolition is completed, the party commander reports by means of previously arranged signals and fixes the necessary markers. He also acts as an observer and watches at the breach.

b. Operating under Fire

To succeed in cutting a breach in a wire obstacle while under fire, the demolition party must work with speed, decisiveness, and daring. It must take advantage of all opportunities to neutralize or impair hostile fire by means of our own fire power or smoke.

In cutting the wire, open wide the handles of the wire cutter, put yourself in a position to support the left (right) elbow, and cut so as to push the wire with the right (left) hand; cut straight through at right angles. The point of cutting should be as near a post as possible.

In placing Bangalore torpedoes under wire obstacles, one man forward generally keeps the head end of the torpedo at the selected post, and two rear men insert the weapon with one shove. Sometimes, depending on the situation, it is advisable to place the torpedo on top of the wire and ignite it.

In disposing of steel wire nets, whether secretly or while under fire, the demolition party should either cover them, clear them away, or destroy them with Bangalore torpedoes. If necessary, have troops lie temporarily on top of the wire net and press it down.


In using the implements to overcome abatis secretly, open a passage, if possible, by cutting off the branches close to the surface of the ground and slowly clearing them away to an adequate extent, with all personnel cooperating.

In making a breach in abatis while under fire, first cut any wires, then cut the branches and remove them to one side. Sometimes it may be better to dig the abatis from their foundations and clear the branches away. Those not firmly secured can often be cleared away by attaching a net to them and pulling.

To destroy abatis by means of Bangalore torpedoes, rest the pipe on the forked part of the branches on the front edge. Remember that simple abatis are often combined with hand grenades, and land mines, and so forth. Demolition or removal in such cases will be carried out after first disarming the weapons.


To enable passage of tanks over an antitank ditch, blast down the sides of the ditch with explosives, or tear down the slopes with implements, or fill the ditch with sandbags and other suitable material, or set up a gabion or framework.1

To destroy iron-rail barriers and abatis, explode grouped demolition charges or Bangalore torpedoes at the base of the obstacles, or clear them away by use of suitable implements.

To enable tanks to cross an antitank pit, lay logs over the top at right angles to the direction the tanks will travel; or place gabions, and so forth inside the pit. In laying logs, be sure that they are firmly placed to prevent slipping. The interval between logs varies with the type of tank. For medium tanks the interval should be not more than 1 1/2 yards; for light armored cars it should be not more than 2 1/2 feet. In putting a gabion inside the pit, it is necessary to consider the distance it will sink by the weight of the tanks. If frames are used, all parts should be connected by wires, or iron fasteners. It will be advantageous to carry along several types of frames, prepared so that we can place them simply and quickly, as desired.

1A gabion is a cylindrical basket woven with open ends; it is filled with earth and generally used as a retaining wall in constructing fieldworks. In modern warfare sandbags are generally used in place of gabions.


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