Although thought to be obsolescent when Japan entered the war, the Aichi D3A with fixed spatted landing gear was the first Japanese aircraft to drop bombs on American targets when aircraft of this type took part in the great raid on Pearl Harbor on 7 December
1941. Designed to a 1936 carrier-based dive-bomber requirement, the prototype was flown in January 1938 with a 529.4-kW (710-hp) Nakajima Hikari 1 radial, Production D3A1 aircraft had slightly smaller wings and were powered by the 745.7-kW (1,000-hp) Mitsubishi
Kinsei 43 radial. A dorsal fin extension considerably improved the aircraft's manoeuvrability, although the armament of only two forwardfiring 7.7-mm (0.303-in) machine-guns, with another of the same calibre in the rear cockpit, was undeniably puny. After limited land-based operations in China and Indo-China, D3As were flown in all major carrier actions during the first 10 months of the war and sank more Allied naval vessels than any other Axis aircraft. Among British casualties in D3A1 attacks were HMS Hermes (the world's first carrier to be sunk by carrier aircraft), and the cruisers Cornwall and Dorsetshire, Heavy losses among D3A1s during and after the Battle of the Coral Sea, however, forced withdrawal by most of the survivors to land bases.