Chapter III: Field Organization

Section II: Arms (Nondivisional)

1. INFANTRY. a. Independent infantry regiments and battalions. (1) The independent infantry regiment or battalion basically will be the same unit as that shown under divisional infantry, modified to perform such special duties as may be required.

(2) Independent mixed regiments. A few units known as independent mixed regiments exist. It is believed that they are independent infantry regiments into which small elements of artillery, engineers, etc., have been incorporated.

b. Independent infantry mortar units. (1) There are two types of mortar units, the infantry mortar units (Hakugeki tai), and the artillery mortar unit (Kyuhō tai). The former, commanded by infantry officers, are mobile units; the latter, commanded by artillery officers, are probably siege. or heavy, semifixed, defense units. It is possible that the independent infantry mortar regiment is largely an administrative or training unit, for only independent battalions so far have been encountered in the field.

(2) Organization. The independent infantry mortar battalion is organized as follows:

Figure 56.

The total strength of the battalion is approximately 900 men, and its armament 36 mortars.

2. CAVALRY. a. The cavalry regiment. The nondivisional cavalry regiment is believed to consist of a headquarters with a signal section, ammunition train and transport, four rifle and saber companies, and a machine-gun company. The organization of rifle and saber companies is identical with that of the division cavalry regiment. The machine-gun company has four platoons, of two machine guns each, and a fifth platoon with eight antitank guns. This type of regiment is found in the independent cavalry brigades.

b. Organization.

Figure 57.

3. TANKS. a. Tank regiment. These units have been reported to have a headquarters, 3 or 4 companies, a regimental ammunition train, and a total strength of 800 to 850 men equipped with 85 to 95 light and medium tanks.

(1) Organization.

Sometimes the light tanks in the above organization are assembled in one company making a fourth, or light tank, company.

Figure 58.

(2) Variant. There are indications that a different organization for the regiment exists, consisting of a headquarters, 1 light-tank company (10 light tanks), 2 medium-tank companies (each with 10 medium tanks and 2 light tanks), and a regimental train. The total strength is estimated at 700 officers and enlisted men with approximately 60 tanks.

b. Cavalry-brigade tank unit. Cavalry-brigade tank units are reported to consist of a headquarters, 2 companies of light tanks, and a unit train. The companies are of 3 platoons each and include 10 light tanks and a company ammunition train. The unit ammunition train carries chemical warfare material and has 6 reserve light tanks. The total personnel strength of the unit is about 350 officers and enlisted men equipped with 30 tanks. There are about 80 trucks included in the trains.

c. Independent mixed-brigade tank unit. The organization of this type unit is believed to include a headquarters, 3 light-tank companies, 1 medium-tank company, 1 light-armored-car company, and a combat train. It is reported to have a total of about 20 medium and 65 light tanks, 25 armored cars, and a personnel strength of about 970 men.

d. Independent tank companies. Reports have been received of independent tank companies. These may be tank companies, either light or medium, detached from a tank regiment for temporarily independent operations.

e. Independent light-armored-car (tankette) companies. These independent companies are divided into two categories by the Japanese, one type being listed as Sokosha (armored vehicle) companies and the second as Keisokosha (light armored vehicle) companies. It is possible that both types are equipped with armored cars, but it is believed that tankettes have been substituted for those vehicles. In either case the company is believed to number approximately 130 officers and enlisted men, divided into a headquarters, four platoons, and a company train, with 17 tankettes or armored cars.

4. ARTILLERY. a. Field artillery. A few independent field artillery regiments and battalions have been identified. Their organization is believed to be similar to that of the field artillery regiment or battalion in the standard divisions, except that the regiment may have only two battalions.

b. Mountain artillery. These units are organized into independent regiments and battalions.

(1) The regiment. The regiment is commanded by a colonel or lieutenant colonel. It consists of a headquarters, a regimental train, 2 battalions (each with three companies), and a battalion train. The regimental strength is approximately 2,500 officers and enlisted men. A regiment seen in action operated approximately 1,500 strong, although it had left most of its horses and large parts of its train in rear areas. Units were as follows:

(a) Regimental headquarters and field train originally consisted of about 750 officers and enlisted men: battalion headquarters, of approximately 230 officers and enlisted men.

(b) Each company had approximately 185 officers and enlisted men, divided into 2 gun platoons and an ammunition platoon. The first gun platoon had 2 guns while the second had only 1 gun and a pioneer squad. (Normal armament is believed to be four guns to a company.)

(c) The battalion field train had about 140 officers and enlisted men. (Overstrength in headquarters was presumably attributable to the necessity of manhandling the equipment.)

(2) The battalion. The independent mountain artillery battalion is believed to be identical with the battalion of the independent regiment. It has a total strength of some 925 officers and enlisted men. In operations the strength has fallen as low as 500.

c. Medium artillery. (1) The regiment. There are several types of medium artillery regiments in the Japanese Army. One type of unit encountered was organized into a regimental headquarters; a regimental train; and 2 battalions, each of 3 firing companies and a train. The regiment was equipped with 24 tractor-drawn Type "96" 150-mm howitzers and numbered approximately 1,500 officers and enlisted men.

(2) Organization.

(Each Co 4—150-mm howitzers)

Figure 59.

(3) Variants. It is likely that other regiments are equipped throughout with 105-mm guns, or are mixed and have one battalion of guns and one of howitzers. The 105-mm gun battalion has been reported to have only two companies of four guns each.

(4) Figures of strength for medium artillery regiments equipped with the older horse-drawn 150mm howitzer would necessarily be higher than those quoted above and might be expected to approximate 2,300 officers and enlisted men.

(5) The battalion. Medium artillery also is organized into independent battalions. The organization and armament of such units probably approximates that of the battalion of the regiment.

d. Heavy artillery. (1) General. Japanese heavy artillery units fall into two categories, mobile and fixed. Some fixed heavy artillery units were designed originally to fulfill a coast defense role for the Japanese Empire. Some, however, also are located to protect strategic centers farther afield.

(2) Organization. The following four types of heavy artillery regiment organization have been reported, but the details are not confirmed.

(a) Headquarters and train.

(b) Headquarters.

(c) Headquarters.

(d) Headquarters.

e. Antiaircraft artillery. (1) General. Japanese antiaircraft artillery is organized into brigades, regiments, battalions, and companies. In addition there are searchlight and other miscellaneous units.

(2) The brigade. These are apparently assigned one to each district army. They are commanded by general officers and composed of two or more antiaircraft regiments.

(3) The regiment. The regiment is believed to consist of two battalions, a company of light antiaircraft and a searchlight battalion.

(4) The battalion. The antiaircraft battalion has alternative organizations; one giving it a main armament of eighteen 75-mm guns, and the other twelve 75-mm guns. (It is believed that some units may be equipped with larger caliber antiaircraft guns.)

(a) The 18-gun battalion.

1. This battalion consists of a headquarters, 3 firing companies and a battalion train. Tabular strength of the unit is approximately 575 officers and enlisted men, with eighteen 75-mm antiaircraft guns and 6 to 9 machine guns.

(2) Organization.

Figure 60.

3. The battalion is commanded by a lieutenant colonel; headquarters and train number some 155 officers and enlisted men. It has been found, however, that these units may enter operations overstrength, the reason for this addition being apparently the inclusion of an extra number of antiaircraft machine guns. Thus one battalion headquarters and train operated with 210 officers and enlisted men equipped with 16 machine guns.

4. Strength for the company is approximately 140 with an armament of six 75-mm antiaircraft guns and 2 machine guns. These units also have been seen in operations well overstrength and with additional machine guns.

(b) The 12-gun battalion. The organization of this unit is similar to that outlined above, except that each platoon has only two 75-mm guns, thereby reducing the battalion armament to 12 guns. Its total strength is estimated at 400 officers and men.

(5) The independent {heavy) antiaircraft company. These companies are similar in organization to those of the battalions. They may have either four or six 75-mm guns and include a train.

(6) The machine cannon company. (a) General. The machine cannon company normally consists of a headquarters, 3 platoons, and a train. Its strength, when motorized, is 160 men, and it has six 20-mm machine cannon and six 13-mm machine guns. The unit also may be horse-drawn or pack, in which cases the strength would be appropriately increased.

(b) Organization.

Figure 61.

(c) Variants. There are variants of the above organization. The company may consist of 4 platoons with 2 machine cannons in each of the first 3 platoons, and 6 machine guns in the fourth platoon. Alternatively, the armament of the unit may be increased from 12 to 16 weapons and the strength to 200.

(7) Field searchlight battalion. The battalion is composed of a headquarters and 2 searchlight companies each of which is divided into a company headquarters and 2 platoons. The platoons are divided into 3 sections each equipped with a searchlight and a sound locator. All equipment is carried on trucks. The total strength is about 450 men, 12 searchlights, 12 sound locators, 50 motor vehicles.

(8) Independent searchlight companies. These units are organized similarly to the company of the battalion.

(9) Other antiaircraft units. Antiaircraft observation units and barrage balloon units are known to exist, but details of their organization are not available. Certain units are listed as field air defense units. They appear to be in the nature of group or higher organization headquarters, controlling all antiaircraft defense in a selected area, and have under their command antiaircraft battalions or companies, machine cannon units, searchlight units, and possibly barrage balloon or antiaircraft observation units. Their size will depend entirely upon the situation and the guns and equipment available. The larger units are commanded by major generals or colonels.

(10) Independent mortar regiments and battalions (artillery). In addition to the independent "infantry" mortar regiments and battalions described in paragraph 1 b, there are other independent mortar regiments and battalions which are commanded by artillerymen and probably are artillery units. The regiments may be composed of a headquarters and 2 or more battalions. The battalions are commanded by majors or captains and probably are divided into 3 companies.

(11) Shipping artillery. Japanese shipping artillery regiments are designed to afford transports and other shipping protection from attack by aircraft or submarines. The regiment normally is composed of a headquarters and 12 companies, but the 2 regiments encountered have included 6 or more additional companies. Tabular organization calls for about 2,300 men to the regiment and about 190 men per company; operating strengths have been about 150 men per company. Companies include antiaircraft gun companies (six 75-mm AA guns each), 75-mm field artillery companies (four 75mm field guns each), and machine cannon companies (six 20-mm machine cannons). They are organized into headquarters, including observation and signal squads, gun platoons, and gun squads. Units usually are broken up to operate in small detachments. Two field artillery gun sections and two machine cannon sections frequently are assigned as the complement of small army transports.

(12) Artillery intelligence units (sound and flash). (a) Artillery intelligence regiments.

1. General. The regiment is commanded by a lieutenant colonel and is divided into a headquarters group, a survey unit, a plotting unit, and a sound detector unit. When horse-drawn, it is believed to number approximately 675 officers and men.

2. Organization.

Figure 62.

(b) Observation balloon regiments and companies. The Japanese are known to have balloon regiments and companies, and such units were employed to give artillery observation during the final assault on Singapore. A motorized balloon company is reported to have a strength of approximately 145 personnel, 23 motor vehicles, and 1 observation balloon.

5. ANTITANK UNITS. a. General. Apart from the antitank gun units included in infantry organizations, there are a number of independent antitank gun battalions and companies as well as cavalry brigade antitank units. Antiaircraft units, especially machine cannon companies, are designed to fulfill a dual-purpose role.

b. Independent antitank battalion. (1) General. The battalion is an 18-gun unit, with a strength of about 500 officers and men. It has been seen to operate with as few as 350. It may be motorized, horse-drawn, or pack.

(2) Organization (motorized).

(3) Its total strength is 490 men and it has eighteen 37- or 47-mm AT guns, and 67 motor vehicles. The above personnel figure should be increased for horse-drawn or pack units.

c. Independent antitank company. The independent company is 6- or 8-gun unit, and, as in the case of the battalion, it may be motorized, horse-drawn, or pack. The organization of the 8-gun unit is shown below.

(Each section 1 gun)

Figure 63.

(1) As a pack unit, the company has 250 men, eight 37-mm guns. 2 light machine guns. 5 riding horses and 76 pack horses. As a horse-drawn unit, the armament would be similar, but the exact strength figure is unknown.

(2) As a motorized unit, the company might number 180 to 200 and be armed with eight 37-mm or 47-mm guns.

(3) Six-gun units are generally similar, with strength decreased proportionately.

d. Cavalry brigade antitank unit. The antitank unit of the cavalry brigade consists of three firing platoons, each of two 37-mm or 47-mm guns, and an ammunition platoon. The total strength is about 140 officers and men with six 37-mm or 47-mm guns.

6. ENGINEERS. a. Engineer groups. These are administrative units commanded by a general officer. They supervise engineer activity and control independent engineer units in a theater of operations.

b. Independent engineer regiments. These units are often attached to divisions in the field. They are divided into the following six different types according to the principal function they fulfill:

They are similar in general organization, consisting of a regimental headquarters, 3 companies, and a material platoon. The tabular strength of each is approximately 1,000 men. The commanding officer is a colonel or lieutenant colonel. Companies are composed of 4 platoons of 4 or more squads each and average 250 to 300 men. The number of motor trucks varies. Personnel carry rifles and probably some light machine guns. It has been noted that regiments are prepared to undertake special duties other than those for which they are designated.

c. Independent engineer battalions. These are known to exist. They are commanded by lieutenant colonels or majors.

d. Independent engineer companies. These units consist of a headquarters and 2 platoons of 3 or 4 sections each. One unit had an operational strength of approximately 165 officers and men.

e. Field road construction units. These are engineer troops organized into a unit of a headquarters and 2 or 3 companies. Duties are general construction, particularly of roads and airfields. Units are commanded by lieutenant colonels and majors; companies are estimated to have about 125 officers and enlisted men.

f. Bridge-building and river-crossing material companies. These units consist of personnel and equipment for bridge-building and river crossings. Strengths vary from 250 to 600, depending upon whether they are draft or motorized.

g. Construction-duty companies. (See shipping units, anchorages, sec. III, par 2 c, p. 50.)

7. CHEMICAL WARFARE. a. The Japanese are known to have a chemical warfare service and organized chemical warfare units. The division units previously have been discussed (see p. 1/m). Besides these, gas battalions and independent gas companies are known to exist. The Japanese have used sternutatory or suffocating gas in China. They have established factories for poison gas manufacture, developed antigas measures, and issued an efficient gas mask to their services. They, therefore, should be considered capable of gas warfare.

b. Picked personnel from all Japanese units are trained in decontamination and antigas work. Although normally acting as regular troops, such personnel are specially equipped to carry out chemical warfare duties; upon occasion they may be formed into temporary smoke (gas) units for the conduct of offensive chemical warfare. It is estimated that there are about 250 such men in an infantry regiment or its equivalent.

8. AIRBORNE UNITS. a. General. The Japanese Army raid-training department has experimented with airborne units, and it is probable that in addition to known parachute units some airborne troops are available for service. The Japanese have referred to an airborne force composed of a glider force and parachute force but give no details.

b. Parachute force. The parachute force has been described as composed of a headquarters, two parachute battalions, and an artillery unit. Total strength is estimated to be about 1,750.

c. Parachute battalion. The battalion is composed of a headquarters and 3 companies with a small nonflying supply section. Companies are of 3 platoons, each of 2 rifle sections and 1 heavy-weapons section. A rifle section has 6 riflemen and an antitank group. The heavy-weapons section has a heavy machine gun section of 9 men, and a cannon section of 5 men. The total strength is estimated to be about 600 to 700.

Figure 64. Organization.

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