Organization of the Imperial Japanese Army
Encyclopedia
Japanese armies
- See article List of Armies of the Japanese Army
In the Imperial Japanese Army (IJA), 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
Army group
An army group is a military organization consisting of several field armies, which is self-sufficient for indefinite periods. It is usually responsible for a particular geographic area...
. Of a similar but slightly lower status was a Haken Gun, or "Expeditionary Army". A Homen Gun ("Area Army" or "Theatre Army") was equivalent to the field armies
Field army
A Field Army, or Area Army, usually referred to simply as an Army, is a term used by many national military forces for a military formation superior to a corps and beneath an army group....
of other nations and a Gun ("Army") was equivalent to a corps
Corps
A corps is either a large formation, or an administrative grouping of troops within an armed force with a common function such as Artillery or Signals representing an arm of service...
in other armies.
Japanese divisions
As the IJA was an infantry force the most common type of division was the infantry division. Later four tank and one parachute division
Teishin Shudan
was a Japanese special forces/airborne unit during World War II. The unit was a division-level force, and was part of the Imperial Japanese Army Air Force...
were formed. The first 18 infantry divisions were originally formed as square division
Square division
A square division is a designation given to the way military divisions are organized. In a square organization, the division's main body is composed of four regimental elements. Since a regiment could be split into separate battalions for tactical purposes, the natural division within a division...
s, and after 1938, most of the remainder were formed as triangular division
Triangular division
A triangular division is a designation given to the way divisions are organized. In a triangular organization, the division's main body is composed of three regimental maneuver elements. These regiments may be controlled by a brigade headquarters or directly subordinated to the division commander...
s with the security divisions being binary divisions. During the course of its existence the IJA organized three Guards
Imperial Guard of Japan
The Japanese is an organization which is dedicated to protection of the Emperor of Japan and his family, palaces and other imperial properties. Following the end of World War II the traditional Guard, which also served as a unit in the Imperial Japanese Army, was dissolved and in 1947 a civil...
Divisions and over 220 infantry divisions of various types (A/Reinforced, B/Standard, C/Counter-insurgency). 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
Imperial Guard of Japan
The Japanese is an organization which is dedicated to protection of the Emperor of Japan and his family, palaces and other imperial properties. Following the end of World War II the traditional Guard, which also served as a unit in the Imperial Japanese Army, was dissolved and in 1947 a civil...
. 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:- Headquarters (300)
- Infantry brigade (11600)
- Headquarters
- Three infantry regiments, each of:
- Headquarters
- Three infantry battalions, each of:
- Headquarters and escort
- Four infantry (rifle) companies
- Machine gun company, with 12 x heavy machine guns
- Battalion gun platoon, with 2 x 70mm Type 92 Battalion GunType 92 Battalion GunThe was a light howitzer used by the Imperial Japanese Army during the Second Sino-Japanese War and World War II. Each infantry battalion included two Type 92 guns; therefore, the Type 92 was referred to as .-History and development:...
s
- Escort and signal companies
- Regimental gun company, with 4 x Type 41 75 mm Mountain GunType 41 75 mm Mountain GunThe Type 41 75 mm mountain gun is a Japanese license-built copy of the Krupp M.08 mountain gun. Originally it was the standard pack artillery weapon. After it was superseded by the Type 94 75 mm mountain gun, it was then used as an infantry "regimental" gun, deployed 4 to each infantry...
s - Regimental anti-tank gun company, with 6 x Type 94 37 mm Anti-Tank GunType 94 37 mm Anti-Tank GunThe was an anti-tank gun developed by the Imperial Japanese Army, and used in combat during the Second Sino-Japanese War and World War II.-History and development:...
s or Type 1 47 mm Anti-Tank GunType 1 47 mm Anti-Tank GunThe was an anti-tank gun developed by the Imperial Japanese Army, and used in combat during World War II.-History and development:The Type 1 47 mm Anti-Tank gun was accepted into service in 1942. The design originated as an improvement to the prototype “Experimental Type 97 47 mm Anti-Tank Gun” ,...
s
- Field artillery regiment (2300)
- Headquarters and escort
- Three field artillery battalions, each of:
- Headquarters and transport
- Three field artillery companies, each with 4 x 75mm field guns (Type 38Type 38 75 mm Field GunThe was a 1905 German design which was purchased by the Empire of Japan as the standard field gun of the Imperial Japanese Army at the end of the Russo-Japanese War.-History and development:...
, Type 90 or Type 95Type 95 75 mm Field GunThe was a field gun used by the Imperial Japanese Army during World War II. It was intended to replace the Type 38 75 mm Field Gun and the Type 41 75 mm Cavalry Gun in front line combat units, but due to operational and budgetary constraints, only a small number were produced, and the Type 38 and...
)
- Cavalry regiment (battalion) (950)
- Headquarters and escort
- Three mounted companies
- Machine gun company, with 6 x heavy machine guns
- Engineer regiment (battalion) (900)
- Four engineer companies
- Materials company
- Transport regiment (1800)
- Up to six companies, with either carts, pack horses, or motor transport
- Divisional signals (250)
- Medical Unit (900)
- Four Field Hospitals, each of 250 personnel (1000)
- Water Purification unit (120)
- Ordnance unit (50)
- Veterinary unit (50)
Total personnel (19,770)
It was common for a Mountain Artillery regiment, with a total of 3400 men and 36 x Type 94 75 mm Mountain Gun
Type 94 75 mm Mountain Gun
The was a mountain gun used as a general purpose infantry support gun by the Imperial Japanese Army during the Second Sino-Japanese War and World War II. It superseded the Type 41 75 mm Mountain Gun to become the standard pack artillery piece of Japanese infantry divisions...
s, 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
Type 91 10 cm Howitzer
The was a howitzer used by the Imperial Japanese Army during the Second Sino-Japanese War and World War II.-History and development:The Type 91 10 cm Howitzer was an orthodox design howitzer, based largely on contemporary French Canon de 105 mle 1913 Schneider howitzers ordered during the late...
or long-range Type 92 10 cm Cannon
Type 92 10 cm Cannon
The was a field gun used by the Imperial Japanese Army during the Second Sino-Japanese War and World War II. It was intended to supersede the Type 14 10cm Cannon in front line combat service.-History and development:...
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
Type 96 15 cm Howitzer
The was a 149.1 mm calibre howitzer used by the Imperial Japanese Army during World War II. It was intended to replace the Type 4 15 cm howitzer in front line combat units from 1937, although it fired the same ammunition.-History and development:...
or long-range Type 89 15 cm Cannon
Type 89 15 cm Cannon
The Type 89 was the main gun of the Imperial Japanese Army heavy artillery units. It was widely used from the Manchurian Incident to the end of World War II, for example, Nomonhan, Bataan and Corregidor Island, Okinawa....
, and an attached tank regiment (battalion). 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 divisional Mixed Brigade was the semi-permanent detachment of a brigade from an Infantry Division with various Divisional support units or units attached from its Corps or Army. This provided a combined arms force of infantry, artillery, cavalry and other support units.
- The Independent Mixed Brigade was a detachment composed of various units detached from other units or independent support units formed together in a brigade. The first two Independent Mixed Brigades, formed by the Kwantung Army in the 1930s was the IJA 1st Independent Mixed BrigadeIJA 1st Independent Mixed BrigadeIJA 1st Independent Mixed Brigade consisted of the following units:* 4th Tank Battalion** 12 Type-89 Medium Tanks** 13 Type-95 Light Tanks** 12 Type-94 Tankettes** 4 Armored Engineer Vehicles...
and the IJA 11th Independent Mixed BrigadeIJA 11th Independent Mixed BrigadeThere were two 11th Independent Mixed Brigades in the Imperial Japanese Army.-The First 11th IMB:The order of battle of the first 11th Independent Mixed Brigade in July 1937:11th Independent Mixed Brigade* 11th Independent Infantry Regiment...
. Each of these brigades were organized in a unique manner and one of them, the 11th was later formed into the IJA 26th Division.- Later a series of Independent Mixed BrigadesIJA Independent Mixed BrigadesThe Japanese Imperial Army had Independent Mixed Brigades that were detachments made of various units detached from other units or independent support units formed together in an independent brigade....
were formed for the purpose of garrisoning the large territories of China captured in the early phase of the Second Sino-Japanese WarSecond Sino-Japanese WarThe Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan. From 1937 to 1941, China fought Japan with some economic help from Germany , the Soviet Union and the United States...
. This variety for China was usually organized with five infantry battalions, an artillery unit, and labor troops. In the Pacific theater they had different and more varied configurations of subordinate units. Towards the end of the Burma CampaignBurma CampaignThe Burma Campaign in the South-East Asian Theatre of World War II was fought primarily between British Commonwealth, Chinese and United States forces against the forces of the Empire of Japan, Thailand, and the Indian National Army. British Commonwealth land forces were drawn primarily from...
, some were hastily formed from line-of-communication troops, and even naval personnel and conscripted Japanese civilian workers.
- Later a series of Independent Mixed Brigades
- The Independent Infantry Brigade; several of these were raised as garrison units, mostly for China.
- The 1st to 4th Amphibious Brigades were formed for use in the Pacific theater. These 3,500 man Sea-Landing Brigades, were used to conduct amphibious assaults on an island but afterwards they stayed to garrison that island.
Regiments
The IJA maintained two types of Independent Regiments, both were used to provide garrisons in occupied areas.- Independent Mixed Regiments: contained an infantry regiment with various support elements such as: an artillery company, engineers, supply and services, etc.
- Independent Regiments: the basic IJA infantry regiment with any attachments.
Detachments
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
CavalryCavalry
Cavalry or horsemen were soldiers or warriors who fought mounted on horseback. Cavalry were historically the third oldest and the most mobile of the combat arms...
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
IJA Cavalry Group
The Cavalry Group of the Imperial Japanese Army was formed on April 21, 1933, consisting of the IJA 1st Cavalry Brigade and IJA 4th Cavalry Brigade. It was originally assigned to the Kwangtung Army. The IJA 3rd Cavalry Brigade was added in October 1937....
on 21 April 1933. There were three cavalry brigades: the IJA 1st Cavalry Brigade
IJA 1st Cavalry Brigade
The Imperial Japanese Army 1st Cavalry Brigade originally formed November 3, 1901.It was assigned to Kwantung Army in April 1933 as part of the IJA Cavalry Group. It was then assigned with the Cavalry Group to Northern China Area Army, June 1938...
, IJA 3rd Cavalry Brigade
IJA 3rd Cavalry Brigade
- Organization :3rd Cavalry brigade* 23rd Cavalry regiment* 24th Cavalry regiment* 3rd Horse artillery regiment* Brigade machine-gun unit* Brigade anti-tank unit* Brigade tank unit* Brigade transport unit...
, and IJA 4th Cavalry Brigade
IJA 4th Cavalry Brigade
The Imperial Japanese Army 4th Cavalry Brigade was originally formed April 1, 1909.It was assigned to Kwantung Army in April 1933 as part of the IJA Cavalry Group. It was then assigned with the Cavalry Group to Northern China Area Army, June 1938. On September 5, 1939, 4th Cavalry Brigade was put...
.
Other units
- Special Research UnitsSpecial Research UnitsSpecial Research Units were covert medical experiment units of the Imperial Japanese Army which conducted biological warfare research and development through human experimentation during the Second Sino-Japanese War and World War II. These units are responsible for some of the most notorious war...
were covert medical experiment units which conducted biological warfare research and development through human experimentation during the Second Sino-Japanese War (1937–1945) and World War II. These units responsible for some of the most notorious war crimes carried out by Japanese personnel. Initially set up as a political and ideological section of the KempeitaiKempeitaiThe was the military police arm of the Imperial Japanese Army from 1881 to 1945. It was not an English-style military police, but a French-style gendarmerie...
military policeMilitary policeMilitary police are police organisations connected with, or part of, the military of a state. The word can have different meanings in different countries, and may refer to:...
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 consisting of regional ethnic forces in occupied areas. Troops supplemented the Kempei Tai and were considered part of the organization but were forbidden by law to rise above the rank of Shocho (Sergeant Major). According to United States ArmyUnited States ArmyThe United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...
's TM-E 30-480 Handbook On Japanese Military ForcesHandbook On Japanese Military ForcesThe US Army's TM E 30-480 Handbook On Japanese Military Forcesis a War Department Technical Manual dated 15 September 1944. It superseded the original TM E 30-480 dated 21 September 1942....
, there were over 36,000 regular members of the Kempeitai at the end of the war; this did not include the many ethnic "auxiliariesAuxiliariesAn auxiliary force is a group affiliated with, but not part of, a military or police organization. In some cases, auxiliaries are armed forces operating in the same manner as regular soldiers...
". 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 AsiaSoutheast AsiaSoutheast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, although the Kempeitai recruited French IndochineseFrench IndochinaFrench Indochina was part of the French colonial empire in southeast Asia. A federation of the three Vietnamese regions, Tonkin , Annam , and Cochinchina , as well as Cambodia, was formed in 1887....
(especially, from among the Cao DaiCao DaiCao Đài is a syncretistic, monotheistic religion, officially established in the city of Tay Ninh, southern Vietnam, in 1926. Đạo Cao Đài is the religion's shortened name, the full name is Đại Đạo Tam Kỳ Phổ Độ...
religious sect), Malaysians and others. The Kempeitai may have trained Trinh Minh TheTrinh Minh TheTrình Minh Thế was a Vietnamese nationalist and military leader during the end of the First Indochina War and the beginning of the Vietnam War.-Biography:...
, a VietnamVietnamVietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
ese nationalist and militaryMilitaryA military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...
leader. Some sources report that the Kempeitai recruited criminals as law enforcers.