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The first A5Ms entered service early in 1937, replacing the Nakajima A2N and Nakajima A4N. The aircraft arrived just in time to take part in the Second China-Japanese War, and made its large scale debut on 19 September 1937, when eighteen A5Ms clashed with a larger Chinese force. The Japanese pilots claimed 26 victories for no losses, and although the claims were exaggerated there was no doubt that the A5M was superior to the Hawk IIIs and Boeing 281s in Chinese service. The A5M units were used to support the attacks on Nanking, Shanghai and Nanchang. During this period they began to clash with Soviet Polikarpov I-153 biplanes and I-16s monoplanes, with both sides claiming then and since to have had the better fighters. In general the two sides were fairly equally matched in early clashes, but the Japanese had the better of the fighting during 1938, and Soviet losses in China began to mount.

The A5M was actually responsible for the first monoplane-versus-monoplane air battles in history, this being between the Japanese and the Chinese in the 2nd Sino-Japanese War. A5M's squared off against American-made Boeing P-26 'Peashooters' in the ensuing action. The P-26's were of similar design with their open-air cockpits, radial piston engines and static faired-over undercarriages. Unfortunately for the P-26's and their Chinese airmen, the A5M proved superior and the A5Ms had little competition for the moment. Used by the Imperial Japanese Navy, the A5M served on through during 1941 the Navy began to pull out of China in preparation for the wider Pacific War that was expected to erupt at any time. At the same time the A6M Zero began to enter service, and the A5M was rapidly phased out in front line units. The A5M was only involved in a few clashes with Allied aircraft. Aircraft from the carrier Ryujo took part in the attack on Davao on Mindanao, and the invasion of the Dutch East Indies, before receiving A6Ms after returning to Japan in April 1942. Land based aircraft in the Marshall Islands clashed with attacking American aircraft from the Enterprise and Yorktown, on 1 February. Finally, on 7 May 1942 two A5Ms from the carrier Shoho managed to get airborne before she was sunk by US torpedoes and bombs. Three victories were claimed by the two A5Ms and four A6Ms that launched, but with their carrier lost the aircraft had nowhere to go - one managed to land on a nearby island but the rest ditched.

The Imperial Japanese Navy delivered a new fighter specification in 1934 calling for an impressive aircraft system capable of 220 miles-per-hour top speed with an excellent climb-rate (interestingly the specification did not include a requirement for ship-borne operations). Though the Mitsubishi and Nakajima firms both produced designs, it was the Mitsubishi firm that got the nod to further their development. The Mitsubishi product became the Ka-14 prototype - of which six total were built, differing in selected powerplants and some design elements - a low-wing monoplane of all-metal construction. First flight of the first prototype (this powered by a Nakajima Kotobuki 5 series radial piston engine of 600 horsepower) was on February 4th, 1935 and sported inverted gull wings which posed some handling issues. The second prototype, featuring a new conventional wing design, became the production A5M after flight testing exceeded all specification expectations (hitting speeds of 280 miles per hour, well above that as required in the initial specification). The revised Ka-14 fitted the Nakajima Kotobuki 2 KAI I engine of 585 horsepower. The system became operational in the Imperial Japanese Navy ranks in the early part of 1937 as the A5M1. Production was handled by Mitsubishi, Watanabe and the Naval Ohmura Arsenal.

To save on weight, the undercarriage featured two fixed main landing gears housed in streamlined fairings. The aerodynamic fuselage was of a tubular shape covered over in flush-riveted aluminum skin and tapering off into the empennage all the while sporting a small cross-section. Wings were low-fitted to the front of the airframe and featured rounded wingtips. The pilot sat well-forward in the design, just aft of the engine compartment, in an open-air cockpit covered only by a windscreen to his front and a raised fuselage spine to his rear. This being a navy aircraft, the A5M was fitted with an arrestor hook and could also sport a centerline fuel drop tank for increased range over water. The design was capped off by a conventional empennage with applicable tail surfaces. Armament was adequate for the time of the A5M's inception into service, this being a pair of 7.7mm Type 97 machine guns fitted into the fuselage. Other than that, Claude has little else to offer in terms of offensive punch.

In this part of the world, the A5M was actually responsible for the first monoplane-versus-monoplane air battles in history, this being between the Japanese and the Chinese in the 2nd Sino-Japanese War. A5M's squared off against American-made Boeing P-26 "Peashooters" in the ensuing action. Before the arrival of the A5M, Japanese airmen were at the mercy of their Chinese counterparts, suffering an inordinate amount of losses with little to show for it. The A5M soon returned air superiority back into Japanese hands in a short time becoming the Empires most important asset of the war. Peashooters were of similar design with their open-air cockpits, radial piston engines and static faired-over undercarriages. Unfortunately got the Peashooters and their Chinese airmen, the A5M proved the superior breed Beyond the Soviet-made Polikarpov I-16s, the A5Ms had little competition for the moment. Beyond that, the A5M served on through the Battle of Coral Sea to which they were, by now, replaced by the A6M "Zeroes" in number and inherent usefulness. As a second-line fighter, they fit the bill perfectly when called to action as kamikaze suicide implements in the waning months of World War 2 while also becoming the mounts of choice for fighter training of a new generation of Japanese airmen.

While the Ka-14 represented the first six prototypes, the A5M1 became the first production model for the Navy, fitting the Kotobuki 2 KAI radial engine of 850 horsepower. This was followed by the improved (though essentially same)A5M2 and A5M2a with Kotobuki 3 series engines of 640 horsepower. The A5M2b, developed from Japanese experience in combat against the Chinese, featured a new streamlined engine cowling over its Kotobuki 3 series radial engines of 640 horsepower and an enclosed greenhouse-style cockpit. This new cockpit proved quite unpopular with Japanese airmen when in practice and was dropped in mid-production. The A5M3a became several prototypes testing the Hispano-Suiza 12 Xcrs series engines of 601 horsepower.

The A5M4 was based on the A5M2b but fitted a different engine and became the definitive Claude. Additionally, these A5Ms were modernized a bit with the addition of an enclosed cockpit. A 35-gallon drop tank was now added for improved ranges and this production series eventually saw use of the Nakajima Kotobuki 41 KAI series 9-cylinder radial piston engine. The engine was rated at 785 horsepower and allowed for speeds of up to 273 miles per hour. Range was listed at 746 miles while a service ceiling of up to 32,150 feet was possible. The A5M4 entered service in 1938 and was quickly fielded against the Chinese for a final death blow. The A5M4 was branched into a two-seat trainer as the A5M4-K of which some 103 were produced by the Naval Ohmura Arsenal.

The Mitsubishi A5M (code-named "Claude" by the Allies) became the world's first shipborne monoplane fighter aircraft when it was inducted into service with the Imperial Japanese Navy in 1937. The system served in some capacity up until the end of the war in the summer of 1945 and saw some 1,094 total examples produced in that span. The system was developed into further variants that included the unsuccessful Ki-18 and the experimental Ki-33 but was best known as the official springboard for the fabulous A6M "Zero" design still to come.

The focus of Japan's aircraft industry was diverted from one project to another at the whim of Army or Navy. Production of a few aircraft with proven and accepted designs would have strengthened the air power of both services. The Army had favored the expansion of its bomber force until the mid-1930s when it switched to fighters. The Army's prime interest in fighter types was due to its success in the Nomonghan conflict. It should be noted that the Army's bomber force was quite remarkable in the Pacific war. The transport aircraft is another matter that the Japanese Army and Navy had shown little interest.

Imperial Japanese Navy aircraft received a designation code very similar to those used by the US Navy. The first Capital letter indicated the mission of the aircraft, and the second Capital letter indicates the company responsible for the original design of the aircraft. A third, lower case letter such as the "c" in A6M5c was used to designate a minor change in the aircraft, such as armament or weaponry. The first number indicates how many different model aircraft of this mission were made. For example, the A6M2 was the sixth in the Carrier Fighter series. The second number indicates the model of the aircraft, which changes with each major change, such as engine or airframe.

Mission                                      Manufacturer
A Carrier fighter                                A   Aichi
B Carrier attack bomber                    B   Boeing
C Reconnaissance Plane                  C   Consolidated
D Carrier Bomber                             D   Douglas
E Reconnaissance Seaplane             F   Observation Seaplane
G Attack Bomber                             G   Hitachi
H Flying Boat                                  H    Hiro
                                                      He Heinkel
J   Land Based Fighter                       J     Nihon Kogata
K Trainer                                         K    Kawanishi
L   Transport                                     M    Special Floatplane
M Mitsubishi                                   MX Special Purpose Aircraft
N Fighter Seaplane                          N   Nakajima
P Bomber                                       P   Nihon
Q Patrol Plane                                R   Land Based Reconnaissance
S Night Fighter                                S   Sasebo
                                                      Si   Showa
V Vought-Sikorsky                          W Watanabe
Y Yokosuka                                    Z   Mizuno

Both the Imperial Japanese Army and Navy had outstanding aircraft. The Army's primary fighter of the early war was the Nakajima K.43 Hayabusa (Peregrine Falcon), a light, little aircraft, with a slim, tapered fuselage and a bubble canopy. The Navy's fighter came to symbolize the Japanese air effort, even for the Japanese, themselves. The Mitsubishi Type "0" Carrier Fighter (its official designation) was as much a trend-setting design as was Britain's Spitfire or the American Corsair. As author Norman Franks wrote, the Allied crews found that "the Japanese airmen were.. .far superior to the crude stereotypes so disparaged by the popular press and cartoonists. And in a Zero they were highly dangerous." The hallmark of Japanese fighters had always been superb maneuverability. Early biplanes-which had been developed from British and French designs-set the pace. By the mid-1930s, the Army and Navy had two world-class fighters, the Nakajima Ki.27 and the Mitsubishi A5M series, respectively, both low-wing, fixed-gear aircraft. The Ki.27 did have a modern enclosed cockpit, while the A5M's cockpit was open (except for one variant that experimented with a canopy which was soon discarded in service.) A major and fatal disadvantage of most Japanese fighters was their light armament- usually a pair of .30-caliber machine guns - and lack of armor, as well as their great flammability.

Besides the two main fighters, the Army's Oscar and the Navy's Zeke and its floatplane derivative, the Rufe, the Japanese flew a wide assortment of aircraft, including land-based bombers, such as the Mitsubishi G4M (codenamed Betty) and Ki.21 (Sally). Carrier-based bombers included the Aichi D3A divebomber (the Val) which saw considerable service during the first three years of the war, and its stablemate, the torpedo bomber from Nakajima, the B5N (Kate), one of the most capable torpedo-carriers of the first half of the war.

Although early wartime propaganda ridiculed Japanese aircraft and their pilots, returning Allied aviators told different stories, although the details of their experiences were kept classified. Each side's culture provided the basis for their aircraft design philosophies. Eventually, the Japanese were overwhelmed by American technology and numerical superiority. However, for the important first 18 months of the Pacific war, they had the best. But, as was also the case in the European theaters, a series of misfortunes, coincidences, a lack of understanding by leaders, as well as the drain of prolonged combat, finally allowed the Americans and their Allies to overcome the enemy's initial edge.

Much has been made of the low performance of American fighters in the earlydays of the Pacific war, but -- ironically -- these aircraft (such as the Curtiss P-40 orGrumman F4F) -- generally were rugged, armored aircraft with self-sealing fuel systems,and thus were highly survivable despite otherwise having unspectacular performance. Armed with four or six .50 caliber machine guns, they had tremendous killing power against more lightly armed and essentially unprotected Japanese fighters and bombers.

Japanese fighter and bomber design over the length of the war began more and more to resemble that of the West. By war's end, Japanese firms were producing rugged fighters and bombers featuring increasing amounts of armor, with protected and self-sealing fuel cells, and the like. One can contrast, for example, the Mitsubishi A6M-2 Type 0 ("Zero" or "Zeke") fighter and the Mitsubishi G4M "Betty" bomber of 1942 with the Nakajima Ki-84 Hayate ("Frank") fighter and the Mitsubishi Ki-67 Hiryu ("Peggy") bomber of 1945.

Betty - A twin-engined, all-metal construction aircraft with fabric-covered control surfaces built by Mitsubishi Heavy Industries Company. It was used in various versions as a land-based bomber (G4M), heavy escort fighter (G6M1), bomber crew trainer (G6M1-K), and transport (G6M1-L2).

Jack - A single-engine, low-wing, land-based interceptor fighter which featured all-metal construction with fabric-covered control surfaces. It was designed by Mitsubishi as the J2M Raiden (Thunderbolt).

Judy - A single-engine, carrier-capable monoplane which featured all metal construction with fabric-covered control surfaces. Designed by Naval engineers at Yokosuka, the D4Y Suisei (Comet), as it was designated by the Japanese, had various versions built at the Naval Air Arsenals in Yokosuka and Hiro, as well as by the Aichi Aircraft Company. Extremely versatile, this aircraft was used as a dive-bomber, reconnaissance plane, land-based night fighter, and kamikaze aircraft.

Kate - A single-engine, low-wing, carrier- based torpedo- bomber which featured all-metal construction with fabric covered control surfaces. The Allies designated the B5N produced by Nakajima as the Kate, and the B5M1 produced by Mitsubishi as the Kate 61 (formerly the Mabel).

Nate - A single-engine, low-wing, fixed-gear, cantilever monoplane which featured all-metal construction with fabric-covered control surfaces. Designed and built by Nakajima as the Ki-27 for use as a fighter, by the end of the war this plane was being used primarily as a trainer or as a kamikaze attack aircraft.

Rufe - The Japanese seeing the need for a water-based fighter in the expanses of the Pacific, modified the A6M2 Zero, and came up with what was arguably the most successful water-based fighter of the war, the A6M2-N, which was allocated the Allied codename "Rufe." Manufactured by Mitsubishi's competitor, Nakajima, float-Zeros served in such disparate climates as the Aleutians and the Solomons. Although the floats bled off at least 40 mph from the land-based version's top speed, they seemed to have had only a minor effect on its original maneuverability; the Rufe aquired the same respect as its sire.

Tojo - A single-engine, low-wing, land-based, interceptor fighter which featured all-metal construction with fabric-covered control surfaces. The aircraft, designated the Ki-44 Shoki (Devil-Queller) by the Japanese, was designed and built by the Nakajima Airplane Company. (It should also be noted that the Allied code name of Tojo which was used for this aircraft was one of several exceptions to the normal naming pattern).

Tony - A liquid-cooled, single-engine, low-wing, land-based fighter which featured allmetal construction with fabric-covered control surfaces. Designated as the Ki-61 Hien (Swallow) by the Japanese, it was designed and built by the Kawasaki Aircraft Engineering Company.

Val - A single-engine, low-wing, fixed-gear, carrier-based dive-bomber which featured allmetal construction with fabric-covered control surfaces. The aircraft, designated the D3A by the Japanese, was designed by the Aichi Aircraft Company and built by Aichi and the Showa Airplane Company.

Zeke - A single-engine, low-wing, carrier-capable fighter which featured all-metal construction with fabric covered control surfaces. The A6M Reisen (Zero Fighter), as it was known to the Japanese, was designed by Mitsubishi, and built by both Mitsubishi and the Nakajima Airplane Company.