1. INTRODUCTION

Considerable information about Japanese small-unit tactics has been printed in previous issues of the Intelligence Bulletin (for example, see Vol. II, No. 5, pp. 64-72, "Small-unit Tactics Used by Japanese at Night"). Some aspects of this subject not previously covered in detail are included in this section. These new details are based on only one Japanese source; this source, however, is believed to be reliable.

2. PATROLLING

On Bougainville Island, the Japanese usually employed two types of patrols: the reconnaissance patrol, which reconnoiters terrain, hostile positions, roads, and so on; and the so-called microphone patrol, which usually destroys communication nets as well as microphone installations. In each case, the strength of the patrol is approximately one squad (10 men), but it may vary according to the situation, mission, and the time available.

If time permits, long-range officer patrols are sent out prior to an attack. Noncom patrols usually are sent out on short and less important missions.

During the last few hours preceding attacks, the microphone patrols, generally led by noncoms, are sent out repeatedly.

Patrols generally study aerial photographs before going out, and one of the main duties of patrols is to confirm information indicated on these photographs.

All patrols are equipped for combat, but are instructed to resist hostile forces only when necessary. The equipment includes a light machine gun.

Just prior to an attack, most patrols stay out one day, or less, but they carry more than one day's rations.

Patrols generally march in a staggered formation, which consists of two single files on either side of a trail or road. The interval between men in each file is about 5 yards. The patrol leader and the light machine- gun operator march at the head. In a withdrawal, these two men remain in the rear until the other personnel clear the danger area.

An overnight patrol generally does not bivouac, but halts for extended periods of rest. The men usually do not sleep, and all remain on watch.

When patrols are out for several nights, they maintain sentries on watch within the bivouac area. Reliefs are made about every 2 hours.

3. APPROACH MARCH

When a company is marching as a unit, normally a platoon is sent about 30 to 40 yards to the front as an advance guard. This is followed by a platoon, the command section, and another platoon, at intervals of approximately 20 yards. About a squad is used for a rear guard. The flanks usually are secured by two men, each about 50 yards to both flanks, but when contact with hostile forces is imminent, a squad is provided on each flank. When a battalion is marching as a unit, about a company of advance and rear guards is provided, and the interval between companies is approximately 50 yards.

The formation used in a night march is exactly the same, but, depending upon the situation and the terrain, the interval between both individuals and units is kept at a minimum. In all cases contact is maintained by connecting files and runners, who are dispatched from each unit to the unit immediately to its rear. During night marches, luminous vines—which can be found in most jungle areas of the Southwest Pacific—are used for individual markings and also as direction guides. These are fastened to the back of each man's pack or may be wrapped around trees to designate the route of advance.

The machine-gun company marches in the main body with the battalion headquarters so that the company can be dispatched immediately to rifle units or sectors where it may be needed.

During a recent operation (Torokina, Bougainville Island), the Japanese normally marched 5 to 7 miles in the daytime, but this is considered to be slow. When pressed for time, they have covered 12 to 13 miles. During these marches there is no particular rate of march and rest is taken as needed. The Japanese consider that it is practically impossible to march at night in the jungle, but if routes are known and planned, 5 to 6 miles can be covered under cover of darkness.

During a halt in a daytime advance, both the rear and the advance guards extend about 15 yards beyond their normal march intervals (45-50 yds.). Each unit observes to its immediate flanks. In special cases sentries may be dispatched to the flanks. The same measures are adopted for night security, but troops are told to close up so that no one is left behind. Troops are ordered to be very quiet.

4. ATTACK TACTICS

a. During the Day

Normally the Japanese move into an assembly area before launching an attack. From this halt, units advance to an area approximately 2 1/2 to 3 miles from the opposing forces and make final preparations. At this point the Japanese leave behind all surplus equipment, and then advance to a line of departure, which is generally located about 500 yards from the hostile positions. At this point deployment is made, and the attack is launched. The tactics employed are much the same as those used in the night attack described in paragraph 4b, except that a normal platoon front is about 50 to 60 yards.

The Japanese heavy weapons are emplaced so that they can fire against hostile heavy weapons and at the same time assist the advancing troops. When a platoon is attacking a position, the attached heavy machine gun normally is located near the center of the platoon. The heavy weapons are controlled by the company commander. He designates the objective and the squad leader in charge of the weapon decides as to its final emplacements.

All communications are maintained by runners. In case the heavy weapons are not under the control of the commanding officer of the attacking unit, the orders have to be issued by higher headquarters as to their emplacement and duties.

b. During the Night

No definite amount of time is allotted for a night attack. The time depends upon such factors as the nature of the terrain, the size of the unit, and so on. However, after arrival at the line of departure, there usually is a 2-hour interval before the attack is launched. The Japanese usually depart from the assembly area at dusk, and favor using dawn for an attack.

When a platoon is attacking a position at night, the normal formation used is as follows:

The rifle squads are deployed on one line and within contact of each other. If a heavy machine gun is attached, this squad will follow the center squad on line and keep within visual and voice contact. When faced with a wire entanglement, one squad breaches the wire, and immediately passes through and deploys to the left.

A second squad then passes through the same breach and deploys to the right. The remaining squad, with the heavy machine gun attached, moves up into a position between the first two squads. The normal front of a deployed platoon is 40 yards. In night operations the surprise element is considered essential.

Contact between a squad leader and the platoon leader is maintained by a runner and from a squad leader to his men by voice and signals. Direction is maintained by selecting intermediate objectives as the advance progresses, or, if time permits, by using vines or markers as guides. The platoon leader supervises the maintenance of direction and controls the advance.

c. General

(1) Infiltration.—No set system of infiltration is followed by the Japanese. Usually a squad at a time is given the mission of infiltrating through the hostile lines. The wire is breached and individuals move up by crawling, or by short rushes. They take advantage of moving during hostile firing and other noisy periods. The Japanese depend solely upon grenades or bayonets for protection, never returning fire. When a suitable route has been established, contact is maintained by a runner who infiltrates back and forth through the lines.

(2) Mortar Company.—For the Torokina operation, the former battalion-gun platoon was reorganized into a mortar company equipped only with 90-mm mortars. The mortars were under the control of the battalion commander—it is unusual for them to be attached to infantry companies. The mortar company normally moves with battalion headquarters and is sent to vital points by order of the battalion commander, according to the situation.

In coordination with heavy machine guns, mortars are often deployed in support of advancing infantry units. Observers are dispatched to a high spot or place where concealment is readily available. In cases where observation is limited, forward observers are used. In these cases, reports from observers to machine guns are transmitted by voice down a connecting file of men stationed at various intervals between the observer and the gun position. Communications between the battalion command post and guns are maintained only by runners. This method is slow and inadequate.

(3) Special Assault Teams.—In breaching wire entanglements, specially trained assault teams are used by the Japanese. An ordinary wire team, consisting of six men and a leader, normally is employed for breaching wire entanglements. Two men are designated for cutting the wire, one man armed with a rifle is stationed to protect the cutters, and two men are held in reserve. However, in the Torokina operation, only two- or three-man teams were used.

Each platoon has three wire cutters, one per squad. Bangalore torpedo and demolition teams come from within each infantry company. The commanding officer controls this party, and, according to the mission assigned, dispatches the type and size of team required to accomplish the mission.

Special assault squads are an integral part of the "working party" found in each battalion. They are composed of approximately 20 men commanded by a sergeant major or a warrant officer. This party carries one flame thrower. For the Torokina operations, each company was organized with a "Special Assault Squad." This squad, composed of 10 to 12 men, carried three Bangalore torpedoes. One man carried and operated aflame thrower, while the number of men required to use a Bangalore torpedo varied with the length of torpedo used. The number of covering riflemen varied with the situation.

(4) Snipers.—The squad leader and platoon commander select snipers from the riflemen of each squad. The selections are made on the basis of intelligence as well as marksmanship. The training of snipers is conducted by each company or battalion, depending upon the situation. First of all, they are given further training in marksmanship, using both moving and stationary targets. Correction of windage is also stressed in this practice. They then receive training in estimating the range with the naked eye. The snipers use the regular Model 38 rifle, fitted with a telescopic sight and a folding bipod. The primary target for snipers is the apparent leaders of the units they may encounter. The maximum effective range for sniping is considered to be 300 yards.

(5) Communications.—All communication is by runners who are dispatched from the lower units. During combat, two messengers familiar with the terrain and local dispositions are dispatched by the squad leader to the platoon commander. Each platoon, in turn, sends out its runners to the company command post; Runners are normally sent out in pairs, but, depending on the importance of the message, this number may be increased. The senior man is put in charge and actually carries the message; no particular formation is used, and the men always travel together. However, during the Torokina operation, a so-called liaison section was organized within each platoon; this section consisted of six men (including officers' orderlies) which were used by the platoon leader as runners and messengers. All runners are instructed to memorize, if possible, the order they are transmitting. However, long orders usually are written down.

Usually no telephones are used, even for communication between company and battalion. However, if one company is dispatched to a distant location for guard duty, telephones may be used for company and battalion communication.