Under the Washington Treaty Japan was limited to 80,000 tons of carriers, but as the treaty exempted vessels under 10,000 tons the naval staff thought that it was worth trying to build an extra carrier inside the limit. The initial design was for an 8,000-ton ship carrying 24 aircraft, but the staff then insisted on adding a second hangar to double the aircraft capacity. This pushed the standard displacement 150 tons over the limit, but nothing was said to Japan's fellow-signatories - the first significant cheating by Japan, but not the last. Even with the illicit extra tonnage the new carrier, called Ryujo, was top-heavy when she was completed in 1933. She was twice rebuilt, with bulges added, some guns removed and the forecastle raised, but the true displacement was now nearer 12,000 tons.
As may be imagined, the Ryujo was not popular in the fleet. Quite apart from her topweight problems, her flight deck was too small and she carried too few aircraft to be effective; she took longer than other carriers to launch and recover aircraft, because of congestion on the deck. However, the experience was put to use in designing the Hiryu and Shokaku classes.
The Ryujo was not part of the main carrier force which attacked Pearl Harbor, but supported the amphibious landings in the Philippines. In April 1942 she attacked Allied merchant shipping and two months later she joined in operations against the Aleutian Islands, but her only major action was the Battle of the Eastern Solomons. The Ryujo was chosen to spearhead an operation to reinforce the defenders of Guadalcanal, and with an escort of a heavy cruiser and two destroyers, was to lure the Americans away from the main force. It worked well, for at 09.05 on 24 August 1942 she was spotted from the air, but other search planes also located the Shokaku and Zuikaku. Ryujo was heavily attacked by aircraft from the Enterprise and Saratoga in the afternoon. In a brilliant attack divebombers and five torpedo-bombers smothered the carrier, scoring an estimated 10 bomb hits and two torpedo hits and escaping without casualties. Japanese records say that only one torpedo hit the carrier, but that was enough to set her on fire from end to end. Her rudder was also jammed, and the doomed ship was unable to steam or steer. Only 300 survivors left the ship, including Captain Kato, and she sank about four hours later.
Specification Ryujo Displacement: 10,600 tons standard, 14,000 tons full load Dimensions: length 180.0 m (590 ft 6 in) overall; beam 20.8 m (68 ft 3 in); draught 7.1m (23 ft 4 in) Machinery: 2-shaft geared steam turbines delivering 65,000 shp (48470 kW) Speed: 29 knots Armour: uncertain Armament: four twin 127-mm (5-in) AA and 12 twin 25-mm AA guns Aircraft: 24 Mitsubishi A6M Zero fighters and 12 bombers Complement: 924 officers and men