Japanese Army Air Force (Longer text)
Module name: Campaign history (Japanese perspective)
This page was contributed by Mr Lex McAulay (Banner Books)

By late 1942, the Imperial Japanese Navy in the southern Pacific area had been heavily engaged in the New Guinea and Solomons campaigns, and it was realised that operations in the airwar in the area required participation from Imperial Japanese Army air units. It was agreed that the Japanese Army Air Force (JAAF) would assume responsibility for the air war over New Guinea, while the Japanese Navy Air Force (JNAF) did so over New Britain, Bougainville and the Solomons.

The first JAAF unit to arrive in December 1942 was 11 Sentai, with some 30 Nakajima Ki-43 Hayabusa fighters. This was an agile aircraft armed with two machineguns and had been successful in previous campaigns. But after only a few battles, by 9 January 1943, 11 Sentai was reduced to 15 aircraft. Pilot losses had been heavy.

The cause of this was the arrival of the US P-38 Lockheed Lightning twin-engined fighter, armed with four .50-caliber (12.7mm) machineguns and one 20mm cannon, all grouped in the nose, which delivered a devastating blow to any target. Designed as a high-altitude interceptor fighter, the P-38 changed the balance of power in the airwar over the South West Pacific Area. Able to out-climb any other fighter in the region, with greater speed at medium and high altitudes, a good range of activity, and formidable firepower, the P-38 could attack from above, fire, and outclimb its opponents, and even return to base over the hostile jungle and seas on one engine. As long as the P-38 pilot used the best features of his aircraft and did not try to fight the nimble Japanese fighters in turning combat, he was almost certain of success.

The fighters first available to the Allies were the Curtiss P-40 Kittyhawk and the Bell P-39 Airacobra. Both were single engined fighters designed for performance at medium and low altitude, but neither was superior to the Mitsubishi A6M Type O, or Zero, the main fighter in JNAF units in the region. The Ki-43 lacked the cannon armament of the Zero, but was equal to the P-39 and P-40. Only the P-38 was greatly superior.

When the P-38 arrived, the ground battle situation had improved in favour of the Allies. The Australian army had gained two notable victories in late 1942, when it defeated the Japanese invasion of Milne Bay, and then defended the main Allied base of Port Moresby against a Japanese force which tried to cross New Guinea from the north, through the Owen Stanley Ranges. The Japanese were forced to retreat from Milne Bay and back through the Owen Stanley mountains, and by November 1942 the Allies had air fields around Port Moresby and also on the northern coast at Dobodura.

The Japanese had naval superiority around New Guinea, but apart from making successful convoy operation from Rabaul, the Imperial Japanese Navy failed to assist the Japanese land forces fighting on the north coast. Naval gunfire bombardment of Allied positions, and especially of the Dobodura airfields, would have made it impossible for successful Allied operations.

For weeks the Allies depended on air supply over the mountains onto the Dobodura airfields, at regular times dictated by daily weather conditions, and the unarmed transport aircraft would have been easy targets for determined fighter operations. But neither the JNAF nor JAAF made any serious effort to halt this vital flow of aircraft from Port Moresby. This Japanese failure to understand the situation and apply their available air power was the opposite of that on the Allied side.

An important factor in Allied success was the ability to intercept and to read the Japanese radio message traffic. The Japanese command was confident that foreigners could not learn Japanese well enough to make use of this, and also confident that no one could break their codes. The Allies managed to do both, in the Pacific and in Europe. Once the Allied command learned that this information was correct, and not false, the intentions and strengths of the Japanese became available. Few Japanese army codes were broken until a complete set of code books was found by Australians dumped in a water-filled shell hole. An unknown Japanese officer had done this rather than burn the code books. From this time the Allied command was able to read the radio traffic of their opponents.

In January 1943, 1 Sentai arrived at Rabaul, and took part in operations around the Solomons area. More JAAF units began to arrive, and a headquarters structure was necessary to admister and command the JAAF force. Therefore the JAAF 4 Air Army was created at Rabaul, New Britain, in mid-1943, and soon moved to Wewak, on the north coast of New Guinea.

In April 1943, the new Ki-61 Hien fighter arrived. This was the only Japanese fighter with a liquid-cooled engine, and was powered by a German Daimler-Benz engine, and armed with German 20mm cannon, but these had to be imported. The Ki-61 was capable of matching speed with the US fighters.

Japanese bombers had serious weaknesses, mainly in defensive firepower and ability to withstand battle damage. The greatest fault in their design was the small bomb load carried and the number of men in the aircraft crew for such a small load. Even Allied fighters could carry as much or more bomb load than some Japanese bombers. These aircraft were good enough for the campaigns in China and South-East Asia, but not good enough for operations against the Allies.

The Japanese air forces had several other major and fatal weaknesses. Success in the war in China and in the early months of 1942 had led to an acceptance that the organisation of air units, their technical and logistical support and their capabilities, were enough to win victory. Air attacks had been followed by advances by Japanese naval and army forces, against poorly equipped inexperienced opponents who had been defeated or who had retreated. It seemed the air forces of Japan were good enough.

In reality, they were not, and soon this was obvious to the pilots, and to the army and navy units which suffered under Allied air attacks. The Japanese rarely returned to bomb a target more than once or twice, and failed to achieve long term destruction. Japan did not possess a true heavy bomber able to fight in formation through strong defences and deliver a powerful bomb load. A reconnaissance flight over a target was soon recognised as the indicator that a bombing raid would follow in one or two days time; defending Allied fighters were ready. Japanese flying units were commanded by an officer who did not fly, but gave detailed orders on the ground to a flying commander. If the plan was disrupted, the formations often became confused. Technical and logistical support was lacking.

There was almost a complete absence among Japanese aircraft companies of radical thought to produce completely new designs with superior performance. Instead, developments consisted of refinements of existing designs. A brief look at books on aircraft used by the combatants in 1939-45 will show the great variety of designs and types used by the Allies, and the continuing similarity of designs from Japan.

An important lack in the Japanese forces was that of a dedicated Intelligence system from frontline units to headquarters, to debrief pilots and crews to acquire an unbiased report on victories and losses and success or otherwise of the mission. Few cameraguns were used to verify claims of victories. This led to acceptance at headquarters of the verbal reports of units about victories, and so to an exaggerated idea of damage inflicted on the Allies. On the Allied side, a system of Intelligence officers and staff was in place to collect and report information without bias, for passage to headquarters, where information from many sources was collated and analysed. Of course, for political and public relations reasons, Allied headquarters sometimes issued exaggerated accounts of success.

The Japanese air forces in the Pacific zones were not adequately supported with a logistical system capable of building and maintaining air bases in the tropics and capable of repairing them when under attack. On the Allied side, large bases and several very large networks of bases were constructed, so that aircraft could divert to an alternate if weather or damage closed one or more. The Japanese bomber force was incapable of destroying these Allied bases, but the Allied force did destroy most Japanese bases and forced the JAAF (and JNAF) to retreat out of range.

In 1943 the P-38 was joined by the Republic P-47 Thunderbolt, another powerful aircraft designed to operate at high altitudes, and armed with eight .50-calibre machineguns. These were particularly effective against Japanese bombers. Both types could absorb much more punishment than the lighter Japanese aircraft, and often returned to base with many bullet holes and other damage.

The Japanese air forces soon were opposed by pilots flying two superior aircraft, able to arrive in the combat area at high level and attack when it suited them, or break off combat at high speed when it was desirable. Despite the numerous claims of victory by JAAF pilots, in truth few victories were scored.

By mid-1943, 4th Air Army comprised 6 and 7 Flying Divisions, each of several Flying Brigades, with fighters, bombers, transport and reconnaissance aircraft.

In August 1943, as a result of erroneous claims of many victories claimed in recent air battles over Marilinan, New Guinea, hundreds of JAAF aircraft were lined up on the airfields at Wewak, But, Boram and Dagua for a visit by senior officers from Rabaul. The Wewak airfields also were part of the aircraft supply route and the repair service, so most aircraft could not be dispersed into the trees. On 17 August 1943, the US 5th Air Force first attacked with heavy bombers at night, then followed this in the early morning with low level bombing and strafing. Surprise was complete and 4 Air Army suffered heavy losses. In the next few days the US squadrons maintained pressure with high level and strafing attacks and fighter sweeps. 4th Air Army lost much of its strength, and some units were reduced to less than 10 aircraft.

The balance of power in the air war over New Guinea had changed. The 5th Air Force maintained pressure along the north coast of New Guinea, then supported the amphibious landing at Lae in September. The JAAF could do little to alter the Allied invasion schedule. In October and November, the 5th Air Force struck at Rabaul and Cape Gloucester in preparation for Allied landings on New Britain. The JNAF and JAAF units lost heavily and failed to affect the Allied plans. Captured Japanese records show that between August 1943 and February 1944, over 700 JAAF aircraft were lost in New Guinea. In early 1944 other Allied landings were made and the JAAF could do nothing to halt them. Any single Allied bomber squadron flew more sorties than the entire JAAF bomber force in New Guinea. The JAAF bomber force was unable to inflict serious damage on the enemy, and the JAAF fighters could not protect the bombers.

The Allied Air Forces under General Kenney demonstrated great flexibility in striking both to the east and to the west with great power, in feats of military expertise totally beyond that achievable by the JAAF.

The resupply process favoured the Japanese, who could fly aircraft from Japan to the battle areas quickly. On the Allied side, even though numerical superiority was achieved, the commanders in the South West Pacific had to convince the high command in Washington DC that more aircraft were necessary, and then wait for these to be produced and sent across the Pacific. Every commander in all theatres of the world war wanted more aircraft of every type for his own theatre, and the European theatre had first priority in everything, as Allied policy was to defeat Germany first.

A constant stream of aircraft of all types flew from Japan along the supply route through the Philippines into the New Guinea battle area, but no sooner was a unit re-equipped than it suffered more heavy losses. Some fighter units lost all their new aircraft in two weeks, and had to go to Manila for more. 248 Sentai, a fighter unit equipped with Ki-43 Hayabusas, produced a document for junior pilots to help them understand the situation. This document admitted the superiority of Allied aircraft, and informed the reader that the only advantage held by the Ki-43 was its ability to turn more tightly than the P-38 or P-47. Allied bombers were acknowledged as having few weak points. The document was defensive in nature, telling what to do to avoid being shot down.

At the same time, Allied fighter leaders produced similar documents for their pilots, but these emphasised the superior qualities of the Allied aircraft and told pilots what to do to shoot down Japanese aircraft, and were aggressive in nature.

In March 1944, the 5th Air Force supported the invasion of the Admiralties, which completed the isolation of Rabaul, and commenced a campaign against the Wewak airfields. By late March, 4 Air Army was totally defeated and forced to move to Hollandia. From 30 March to 16 April, 5th Air Force pounded Hollandia and also heavily attacked other areas in New Guinea. On 22 April 1944, Hollandia was invaded, and the JAAF was forced further west into the Halmaheras and Celebes. In May, Biak was invaded.

The Allied command was assisted by radio intercept information, which contained messages explaining exactly what the Japanese command thought would occur, where, and what they had done to counter expected Allied moves. The Japanese expected further operations around Rabaul, and at Madang or Wewak. The Allies, under General Douglas MacArthur, moved even further west, to Hollandia, and left those Japanese forces east of there to remain, isolated, for the rest of the war. For political reasons to do with post-war intentions in New Guinea, Australian forces remained to fight and defeat the by-passed Japanese.

Allied airpower had sunk many ships, and commanded the seas as well as the sky. The men of the JAAF units at Wewak were told to walk west, first to Hollandia, and then to Sarmi. Hundreds died; entire units disappeared. Of some, only a few ever returned to Japan. At Wewak, some JAAF men fought as infantry against Australian army units, but few survived.

By July 1944, 4 Air Army almost ceased to exist and some formations and units were disbanded. Around But and Dagua, over 400 wrecked JAAF aircraft were found, and more than 400 were found around Hollandia. Wrecks littered the ground around other airfields along the New Guinea coast.

Further Allied landings were made, always west and north, and in October the Philippines were invaded. The JAAF and JNAF in the New Guinea area had been destroyed.

The failure of the JAAF (and JNAF) was due to the following factors: a false impression of success possible with the existing equipment and procedures, after the early victories; lack of real co-operation between the air, land and sea forces; commanders who did not really understand modern airwar; unit commanders who did not fly on operations but issued detailed orders to those who did; no dedicated Intelligence system to acquire accurate information on effectiveness; no heavy bomber in the correct meaning of the term; a failure by higher command and industry to design and produce better aircraft, instead of making small improvements; most importantly, a lack of radical thought among aircraft designers to conceive aircraft capable of meeting the problems facing an air force operating across the Japanese Empire.

Japanese Army Air:




This page was last updated on 23 June 2003.
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