Organization of the Imperial Japanese Army


This article details the organization of the Imperial Japanese Army.

Basic organisational structure

At the outbreak of the Second World War, the basic structure of the Imperial Japanese Army was as follows:
In the Imperial Japanese Army, the term Gun, literally meaning "army", was used in a different way to the military forces of other countries. A So-Gun, meaning "General Army", was the term used in the IJA for an army group. Of a similar but slightly lower status was a Haken Gun, or "Expeditionary Army". A Homen Gun was equivalent to the field armies of other nations and a Gun was equivalent to a corps in other armies.

Divisional

As the IJA was an infantry force the most common type of division was the infantry division. Later four tank and one parachute division were formed. The first 18 infantry divisions were originally formed as square divisions, and after 1938, most of the remainder were formed as triangular divisions with the security divisions being binary divisions. During the course of its existence the IJA organized three Guards Divisions and over 220 infantry divisions of various types. On 7 December the IJA had two divisions serving in Japan/Korea and 50 serving abroad, most in China. During the war another 117 were raised for foreign service and 56 were raised for national defense. These totaled 223 including the Imperial Guard. Of this total no more than 35, that is one fifth of the IJA infantry division total, fought in the Pacific theatre.

Organisation

The Standard, or Type "B" division was organised as:
Total personnel
It was common for a Mountain Artillery regiment, with a total of 3400 men and 36 x Type 94 75 mm Mountain Guns, to be substituted for the Field Artillery regiment, especially for operations in rough terrain. A Reconnaissance regiment, with a mix of mounted, motorized infantry and anti-tank companies, could replace the Cavalry regiment.
The Reinforced or Type "A" division generally substituted medium artillery companies with 4 x Type 91 10 cm Howitzer or long-range Type 92 10 cm Cannon for one or more field artillery companies in the field artillery regiment. It might also have an attached medium artillery battalion with three companies each of 4 x Type 96 15 cm Howitzer or long-range Type 89 15 cm Cannon, and an attached tank regiment. Conversely, the Type "C" division would lack artillery and other supporting arms.

Brigades and equivalents

The Japanese Imperial Army had two types of Mixed Brigades.
The IJA maintained two types of Independent Regiments, both were used to provide garrisons in occupied areas.
Detachments were particular military formations of the Imperial Japanese Army. Similar to German Kampfgruppen, these detachments were usually a force of infantry, artillery, armor, and other support units which were temporarily assigned for independent action and had a special mission. They were usually named after their commanders or the area in which they were to operate, and could be any size below division.

Cavalry

units were formed in regiments most were either operating attached to infantry divisions or directly under a brigade attached to an army prior to the formation of the IJA Cavalry Group on 21 April 1933. There were three cavalry brigades: the IJA 1st Cavalry Brigade, IJA 3rd Cavalry Brigade, and IJA 4th Cavalry Brigade.

Other units

Unit 731

were covert medical experiment units which conducted biological warfare research and development through human experimentation during the Second Sino-Japanese War and World War II. Unit 731 responsible for some of the most notorious war crimes. Initially set up as a political and ideological section of the Kempeitai military police of pre-Pacific War Japan, they were meant to counter the ideological or political influence of Japan's enemies, and to reinforce the ideology of military units.

Kempeitai Auxiliary units

Kempeitai Auxiliary units consists of regional ethnic forces in occupied areas. Troops supplemented the Kempeitai and were considered part of the organization but were forbidden by law to rise above the rank of Shocho. According to United States Army's TM-E 30-480 Handbook On Japanese Military Forces, there were over 36,000 regular members of the Kempeitai at the end of the war; this did not include the many ethnic "auxiliaries". As many foreign territories fell under the Japanese military occupation during the 1930s and the early 1940s, the Kempeitai recruited a large number of locals in those territories. Taiwanese and Koreans were used extensively as auxiliaries to police the newly occupied territories in Southeast Asia, although the Kempeitai recruited French Indochinese, Malaysians and others. The Kempeitai may have trained Trinh Minh The, a Vietnamese nationalist and military leader. Some sources report that the Kempeitai recruited criminals as law enforcers.

Recruitment

Conscription

Conscription of all able-bodied males aged 17 to 40 was instituted in 1873 and revised in 1927. Once called up, candidates were given a medical examination and classified as one of the following:
Upon receiving their classifications, peace-time Class I-A recruits were enlisted by lottery into either the jobi hei-eki category, consisting of the gen-eki and the yobi-eki sub-categories, or into the kobi hei-eki category. Those in the "gen-eki" sub-category would serve for two years in the army or three in the navy. After this period, they would be placed on the primary reserve service list for five years and four months in the army or four years in the navy, and would be subsequently placed on the secondary reserve service list after 10 years in the army before being placed on the national service list after 17 years and four months of army service. A similar but less stringent path was set out for those enlisted into the primary or secondary reserve categories; they would also end their service on the national service list. The least rigorous path was for those enlisted into the hoju hei-eki, who would end their service on the national service list.
In peace-time, Class II recruits were not recruited, but were assigned to national service. In wartime, Class II B-1 and Class II B-2 recruits were enrolled into the hoju hei-eki category, with II B-1 recruits enlisted into the first supplementary territorial army and naval volunteer reserve and II B-2 recruits enlisted into the second supplementary territorial army and naval volunteer reserve, respectively. II B-1 recruits would serve for two years and four months in the territorial army or one year in the naval volunteer reserve; II B-2 recruits would serve for 12 years and four months in the territorial army or 11 years and four months in the naval volunteer reserve. Upon reaching the age of 40 in peace-time, all soldiers in Classes I and II would be placed on the national service list and released from regular duties.
In practice, total conscription of the available population was only instituted during the Second World War. Before then, only a proportion of the secondary reserve service had been called to active duty, during the Russo-Japanese War. Class III-C recruits were automatically assigned to national service if necessary. Conscripts classified as Class IV-D were reexamined the following year; if they could not be reclassified into any of the first three classes, they were officially exempted from all military service. Sole supporters of families and criminals sentenced to over six years penal servitude were automatically listed as Class IV-D and exempted from all service. Students at certain higher secondary schools were classified as Class V-E until they had finished their studies or upon reaching the age of 27, whichever came first. Japanese students studying abroad were also classed as Class V-E until reaching the age of 37.
From December 1927, conscripts who had completed a course of study with the requisite marks at a government-run Young Men's Training Institute, the curriculum of which included 200 hours of military training, could have their period of active service reduced to 18 months. Normal-school graduates with the requisite marks had their active service reduced to five months. Graduates of middle and higher schools who had completed courses in military training with the requisite marks were required to serve one year for middle-school graduates or for 10 months for higher-school graduates.

Salaries, benefits and pensions

Salaries and pensions for Imperial soldiers and sailors were very low by Western standards. On the eve of the Second World War, the yen had a value of $0.23. No true exchange rate existed for the yen during the war years, and wartime inflation reduced the yen to a fraction of its pre-war value.
Officer cadets were paid a yearly salary of ¥670. Second lieutenants were paid ¥850 yearly, lieutenants ¥1020–1130 and captains ¥1470–1900. Majors were paid ¥2330 yearly, lieutenant-colonels ¥3220 and colonels ¥4150. Major-generals were paid ¥5000 yearly, lieutenant-generals ¥5800 and full generals ¥6600.

Arsenals

The Imperial Japanese Army managed various Arsenals: