Japanese Forces 1939/40
Strength and organisation of the Imperial Army, Air Force and Combined Fleet

The Japanese Army was a mirror of Japanese society before 1945. It contained a peculiar amalgam of medieval attitudes and modern materiel, for the Army still followed the code of Bushido which upheld the virtues of man-to-man combat in a machine age, and demanded that the Japanese soldier die rather than surrender.
The political influence of the Japanese Army had substantially increased in the years between the two world wars. The Army saw Japan's salvation in China: Japan should secure the vast resources of the Asian mainland by carving out for herself a continental empire. The Army consequently viewed the Soviet Union as Japan's most dangerous enemy - a power which had traditional interests in North China. The Navy looked to the Pacific Ocean, and particularly to the South West Pacific, with the rich prize of Malaya and the Dutch East Indies as the means by which the resources vital to the maintenance of Japan as a great power could be seized. The Navy, therefore, regarded the world's two greatest naval powers, Great Britain and the United States, as Japan's most deadly enemies. It was no coincidence that the two services shaped Japan's strategy to suit the exclusive capacity of either the Army or the Navy. Before 1941 the Army had most of its' own way.

Japan seized Manchuria in 1931 and the province of Jehol in 1934. Three years later the Japanese Army embarked on a full-scale undeclared war against China. The Japanese aimed to destroy the Chinese Army in the field and thus bring the country to its knees quickly; this would avoid the colossal task of trying to conquer and hold the vast spaces of China. The Japanese generals failed. The Chinese Army was more elusive and remained intact, and Japan's need to keep large forces on the Chinese mainland was a limiting factor on her strategy throughout World War II.

The peacetime strength of the Japanese army was 17 divisions.
By 1940 it had 2 divisions in Japan and Korea, 12 in Manchuria and 27 in China (total 41 divisions).
Even in 1943 the commitment in China still amounted to 25 infantry divisions, 1 armoured division, 11 mixed brigades, 1 cavalry brigade and 1 flying division - a total of 620,000 men and 14,000 vehicles. This force, known as the Kwantung Army, was called upon to provide a constant stream of reinforcements for the Pacific War, and by 1945 its units were understrength and too weak to pose any real threat.

The Manchurian Army proper in 1939 had a strength of some 75,000 men in infantry and cavalry units.

Basic Japanese fighting units:

Heavily-loden Japanese soldiers are pictured while crossing a pontoon bridge in China. They wear M98 field service uniforms and carry bolt-action 6.5mm Ariska rifles. The enormous distances which warfare in China necessitated were hard to cover, especially for an Army as unmechanised as the Japanese. Logistics were a constant problem.

Army Air Force:

There was no independent Japanese air force. The Army and the Navy each had their own air service. Each was nominally controlled by the Emperor. Actual control was vested in the General Staff, the Army and Navy Ministries and the Inspector General of Aviation.
The function of the Japanese Army Air Service was to provide support for the ground troops and to conduct counter-air force operations. It was not expected to initiate strategic operations on its own behalf, as was the case with the RAF for instance.
The Air Service was relatively small at the outbreak of war and Japan's highly-trained pilots were soon casualties. Their replacements lacked the necessary flying ability to take on the growing technical and numerical superiority of the Americans. Partly as a response to this shortage kamikaze aircraft were introduced. The kamikaze aircraft was simply an aimed bomb in which the pilot sat over an explosive charge and aimed the aircraft at the target. First used at Leyte Gulf, these planes caused some consternation to the American forces; but overall their effect was negligible to the final outcome of the conflict.
The Japanese Army Air Service was organised into five air armies with clear areas of operations. Coordination was achieved between the Army and the Air Service by placing the air forces in each theatre under the command of the theatre commander. The largest Japanese tactical organisation was the air division, two or more of which would form an air army. Beneath this was the air brigade; two air brigades formed an air division. The composition of the brigade was flexible. Its HQ was small and concerned primarily with tactical planning. It was usually composed of three or four air regiments; each regiment was equipped with the same type of aircraft (fighters, or light or medium bombers) divided into three or four companies. The company was the most important operational unit; it was normally of nine aircraft, divided into three sections, each of three aircraft.

The total strength of the Japanese Army Air Service in 1940 was 36 fighter (324 planes), 28 light (252 planes) and 22 medium bomber (198 planes) and 29 reconnaissance companies (261 planes), with a personnel total of 33,000 officers and men.

Naval Air Force:

Apart from 370 training and reserve machines, the Japanese Naval Air Force totalled aprox. 1,400 aircraft. There were 660 fighters, 330 carrier-borne strike aircraft, 240 twin-engined shore-based torpedo-bombers specifically intended for fleet cooperation, and 520 flying boats and seaplanes.
All these aircraft were organised in the Combined Air Fleet, based at Kanoya, and were subduvided into the 1st Air Fleet (the Carrier Fleet) and the 11th Air Fleet (under Vice-Admiral Nishizo Tsukuhura) shore-based in Formosa and Indo-China. The fleets were further divided into air flotillas (each commanded by a rear-admiral), which where themselves composed of two or more air groups. Each air group comprised a base unit and 12 to 36 aircraft with 4 to 12 in reserve, depending on size. The combat formation was the air division of about nine aeroplanes.

Two Mitsubishi A5M Claude over China. These fighters turned the tables on the Chinese and achieved complete air supremacy.

Japanese Navy:

The Prime Minister presided over Imperial General Headquarters (GHQ) which was split in two sections - Army and Navy. Holding positions at Imperial GHQ were the Navy Minister and the Chief of the Navy General Staff, Admiral Osami Nagano. Other officers and departments handled the responsibilities of staff and ministry.
Executing the naval instructions emanating from Imperial GHQ was the C-in-C of all seagoing warships. This was Admiral Isoroku Yamamoto, and following his death in April 1943, his successors were Admiral Mineichi Koga, Admiral Soemu Toyoda (from March 1944) and Admiral Jisaburo Ozawa (from May 1945 to the end of the war).

In addition to the responsibility for implementing strategic moves generally, they were also expected to take tactical command of the most important operation in progress. Admiral Yamamoto flew his flag in the battleship Nagato until the superbattleship Yamato was commissioned on 16 December 1941. There was a constant restriction on radio communication whenever she put to sea, and at such crucial times, the C-in-C was out of touch with all but the immediate situation.
From May to September 1944, the C-in-C's flagship was the Oyodo, a command cruiser for combined striking forces of submarines and aircraft. Although permanently anchored first in Tokyo and then in Hiroshima Bay, her communications facilities proved inadequate. The HQ of C-in-C Combined Fleet was finally located at Keio University in the Tokyo suburb of Hiyodashi.
As its name implies, the Combined Fleet (Rengo Kantai) was just that - the whole Navy. All other units, regardless of function or size, were designated as tai or butai, both of which could be translated as corps, force or body. The intelligence sections of other navies assigned the terms fleet, squadron and division for the purpose of description as appropriate.
It was customary for groups of smaller warships to be led by a bigger one. Thus four destroyers made up a division, four divisions a destroyer squadron, plus a cruiser as flagship. A somewhat similar organisation existed for submarines.
For administrative purposes, the Combined Fleet was divided into lesser fleets according to function.

The Kirishima, one of the four Kongo class battlecruisers build during World War I. They were all rebuild from 1933 to 1940 as fast battleships with eight 36.6cm guns and a top speed of 30 kn.