100 years ago, the first purpose-built aircraft carrier was commissioned into service

IJN Hōshō, the world’s first purpose-built aircraft carrier and Japan’s first aircraft carrier was commissioned into service 100 years ago today.

Japanese aircraft carrier Hōshō Tokyo Bay.jpg
By Unknown author – Kure Maritime Museum, Japanese Naval Warship Photo Album: Aircraft carrier and Seaplane carrier, Supervisory editor: Kazushige Todaka, p. 12., Public Domain, Link

The Hōshō was the second warship, after the British HMS Hermes, to be designed and built specifically as an aircraft carrier. It was launched before the Hermes and completed its construction earlier.

The Hōshō was originally designed as a seaplane carrier with a forward flying-off deck, 32 aircraft. However, the design was revised after Japanese observers with the Royal Navy reported the benefits of being able to land aircraft on a ship. The new design was based on the HMS Furious, which had received a rear flight deck in 1918. The Hōshō was to be capable of 30 knots and have a forward flight deck, island and funnels amidships, and a large hangar aft. After observing landing trials on the Furious and HMS Argus, the first flush-decked aircraft carrier, the Hōshō’s design was further revised in April 1919. The island was removed and the funnels were moved to one side to create a full-length flight deck, and the ship was reclassified as an aircraft carrier. The Hōshō’s hull was based on that of a large cruiser and it had a small island. Its three funnels were mounted on the starboard side and could be swiveled to lie horizontal during flight operations. Its designed speed was reduced to 25 knots, based on British experiences during World War I.

Hōshō could carry up to 15 planes at a time, depending on how much space was available in its hangars. When it was first commissioned, it had nine Mitsubishi 1MF fighters and three to six Mitsubishi B1M3 torpedo bombers. In 1928, the fighters were replaced with newer A1N1 models. A few years later, the air group included Nakajima A2N fighters and Mitsubishi B2M torpedo bombers. In 1938, the Hōshō had Nakajima A4N fighters and Yokosuka B3Y bombers on board. In 1940, the air group was updated with Mitsubishi A5M “Claude” fighters and Yokosuka B4Y1 “Jean” bombers

The carrier first saw combat during the Shanghai Incident. A conflict that began in January 1932 between Japan and China over control of the Chinese city of Shanghai. The incident began when a group of Chinese soldiers fired on a group of Japanese civilians, killing several of them. In response, the Japanese military launched a full-scale invasion of Shanghai, which resulted in a number of battles and skirmishes between the two sides. Hōshō arrived at the mouth of the Yangtze River on Feb. 1st together with carrier Kaga. On Feb. 5th, its planes were involved in the first aerial combat of the Imperial Japanese Navy, when three fighters escorting two attack aircraft engaged nine Chinese fighters over Shanghai. One Chinese fighter was damaged, though the Japanese pilots did not claim any victories.

During the Second World War, Hōshō did not participate in the Pearl Harbor attack but was involved in the Battle of Midway. The carrier was assigned to provide air cover for the Main Body, consisting of three battleships. That force was 300 nautical miles behind the Japanese carrier strike force and was unlucky to escape from destruction by the American forces. The planes from Hōshō helped remnants of the Japanese carrier strike force to rendezvous with the Main Body.

She was reassigned as a training aircraft carrier for later part of the war and was stricken from the navy list on Oct. 5, 1945. Her post war new mission was to repatriate overseas Japanese and a total of nine such trips were made in 1946 before the carrier was scrapped in September that year.