The Japanese air forces, divided into separate army and navy air arms, had developed under the influence of foreign aviation.
In 1911 two Japanese army officers received air training in France, and they were followed by a few more officers during the next two years. In 1919 a French mission comprising some 60 airmen arrived in Japan to assist in army air training; in the same e army established an aviation section. By 1920 the first military aviation school had been opened near Tokyo; two additional schools were established in 1922.
Organizational changes came with the expansion of the Japanese Army Air Force, which soon occupied a place along with the infantry, field artillery, and cavalry. Before the end of the 1930s, the post of Inspector General of Military Aviation had been created, making one commander directly responsible to the Emperor for the training of the air force.
The Japanese Navy Air Force had a similar history in its origin, development, and gradual assumption of importance.
The functions of the two Japanese air forces were clearly divided. The army air force was designed solely to support the army ground forces, while the l air force, in addition to supporting the fleet, was responsible for coastal defense, convoy protection, and sea and antisubmarine patrols. There was apparently little co-operation between the two forces, for they had developed independently and they were under the direction of the respective army and navy commanders who showed little desire to coordinate the activities of the air arms.
In the period of 1937-41, Japanese air power received its first extended test in combat. In 1931 the Japanese army had moved into Manchuria, and from that stronghold drove into China in the summer of 1937. The air forces of the aggressor had virtually an open sky, for the weak Chinese Air Force was unable to offer strong opposition.
Under the stimulus of civil war, from 1911 to 1928, the several factions in China had developed air services consisting of a few obsolete aircraft purchased from abroad. Upon establishment of the central government in 1928, a more stable program was possible, and during the thirties, expansion and improvement of Chinese military aviation were accomplished with the aid of foreign technical advisers.
But the Chinese Air Force was in no sense prepared to meet the relatively modern air force with which the Japanese opened the war in 1937. By the end of the year, the Chinese Air Force had been almost completely destroyed. Assistance from the Soviet Union and other nations enabled the Chinese to continue their air opposition, but their efforts were ineffectual. The lack of a modern training program, inadequate maintenance and repair facilities, and deficiencies in organization accounted for much of the weakness of the Chinese force.
At the outbreak of the conflict in 1937, air combat on both sides was poorly executed, although there was no question as to the courage of either Chinese or Japanese pilots. Bombing was inaccurate, but the Japanese improved with practice and they revealed a talent for modifying their tactics in order to meet changing tactics of their opponents.
The Chinese, forced to fight a defensive war on their own territory, concentrated on improving their interceptor aviation. in the early days of the fighting, Japanese bombers without pursuit protection made daylight attacks on Nanking and other cities, but following a few disastrous encounters with Chinese pursuit planes, the bombing halted until pursuit planes could be brought from Japan to provide the necessary protection.
Japanese bombing formations, which at first numbered about nine planes, soon increased to an average of twenty-seven planes per wave of bombers. The attacks, against both Chinese troop concentrations and Chinese cities, were usually preceded by one or two reconnaissance planes which gathered weather information and intelligence of enemy air dispositions. Carrier- and shore-based planes of the naval air force operated against the Chinese, particularly in attacks on Chungking and in support of ground troops in the Shanghai and Tsingtao areas.
The air force of the Japanese army participated on a larger scale, and personnel were rotated frequently in order to give combat experience to more airmen. In the Russo-Manchurian order fighting which broke out in May 1939, the Japanese Army Air Force received a much more severe and devastating test of its strength. The Soviet Air Force, designed primarily as immediate support to the Red Army, administered a resounding defeat to the Japanese force, which committed almost its entire strength to the engagement and lost approximately 500 planes and 150 pilots.
According to the Japanese, their losses were worthwhile because they brought about important changes in organization, training, and tactics. These changes, however, were accompanied by no marked departure from existing concepts of air warfare, and the chief development came in an accelerated rate of expansion.
As the border fighting ended in September 1939, the poor record of the Japanese Army Air Force led foreign observers to conclude that the army’s force was inferior in both training and efficiency to the naval air force. There was some justification for such a belief. Training in the army flying schools was devoted almost exclusively to pilots, and training of other aircrewmen was largely neglected until their assignment to tactical units.
The navy, on the other hand, gave closer attention to the training of all members of the crew, and by 1941 its training program was designed to turn out annually some 2,500 navigators, bombardiers, gunners, and flight engineers. At the same time, the navy was training about 2,000 pilots a year, while the army was turning out pilots at the rate of approximately 750 a year. In equipment, too, the army air force lagged behind the navy air force. The latter possessed some excellent four-engine patrol bombers, while the army had nothing heavier than a two-engine bomber.
Prior to 7 December 1941, the army air force flew almost exclusively over land, and its longest-range bombers had an operational radius of only some 500 miles. The navy’s force had been trained to operate over water with a radius of about 800 miles. Both forces, however, had a number of well-tried torpedo bombers, dive bombers, and level bombers, reconnaissance and transport planes, and several models of the Zero fighter–a fast, highly maneuverable but somewhat vulnerable plane with a maximum speed of approximately 350 miles per hour.
The planes were hybrids of foreign designs, with German influence being particularly notable after 1936 when Japan threw in her lot with Germany by signing the Anti-Comintern Pact. By 7 December 1941 Japanese air strength consisted of some 27,000 aircraft assigned to fully trained air units.
Approximately 6,000 pilots had been graduated from air schools or training units, 3,500 of which were assigned to the navy and the remainder to the army. About 50 percent of the army pilots had been in combat either in China or in the border fighting against the Soviet Air Force, while 10 percent of land-based navy pilots had participated in the Chinese operations.
Some 600 of the best navy pilots were assigned to aircraft carrier units. In contrast to the 200 hours in primary, basic, and advanced training then being given to Air Corps cadets in the United States, the Japanese pilots were receiving about 300 hours in training units before being assigned to tactical units. The average first-line Japanese pilots in 1941 had about 500 flying hours, and the average pilot in the carrier groups which were destined to begin hostilities against the United States had over 800 hours.
Though somewhat discounted by officials of other nations, the Japanese air forces had now reached a peak of efficiency, at any rate in their first-line strength, which gave them a commanding position in the Pacific.