Japanese aircraft carrier Taiyō

Taiyō was the lead ship of Taiyō-class of escort carrier operated by the Imperial Japanese Navy in World War II.

Civilian service
The Kasuga Maru (春日丸) was a Japanese ocean liner owned by Nippon Yusen Kaisha. When first launched, this ship was named after an important Shinto shrine.

The ship was built by Mitsubishi at Nagasaki on the southern island of Kyushu. Work on the Kasuga Maru was completed in 1939. The ship was built by Mitsubishi Shipbuilding & Engineering Co. at Nagasaki, Japan. The vessel's pre-war design anticipated passenger service; but when work was completed, the onset of war had created somewhat different priorities.

The 17,150-ton vessel had a length of 591 feet (180 m), and her beam was 73 feet (22 m). The ship's steam turbines and twin screw propulsion produced an average speed of 18-knots.

The vessel was created as a sister ship of the Yawata Maru, and the Nitta Maru. None of the three survived the Second World War. Each in succession was re-fitted as a troopship; and each was later converted to an aircraft carrier.

The 17100 LT ocean liner Kasuga Maru (春日丸) — owned by the Nippon Yusen shipping line — was laid down in the Mitsubishi shipyard in Nagasaki in January 1940 and launched in September of the same year.

Military service
In February 1941, before she was completed as a passenger ship, Kasuga Maru was requisitioned for transportation of military stores and personnel. In 1942, its sister ship Yawata Maru was recommissioned as the Japanese aircraft carrier Unyō and the Nitta Maru was recommissioned as the Japanese aircraft carrier Chūyō.

After she completed a few personnel transport voyages, it was decided to convert her to an escort carrier. The conversion took place in Sasebo from May–September 1941. Her flight deck measured 150 x and was equipped with two elevators. With no island, catapults or arresting gear, Kasuga Maru was classified as an auxiliary carrier. On 31 August 1942, she was renamed Taiyō (大鷹, “goshawk”) and reclassified as a warship. (Many experts dispute the lack of arresting gear on the Taiyo and her sisters, and while photographic evidence is lacking, the Taiyo during her service life operated aircraft which required arresting gear to land aboard a carrier.)

Taiyō was used primarily for flight training and aircraft transport. She was torpedoed and hit by United States Navy submarines on several occasions: on 28 September 1942, south of Truk by USS Trout (SS-202), then on 9 April 1943 by USS Tunny (SS-282) and on 24 September 1943 by USS Cabrilla (SS-288). Each time, she was repaired and put back to service. During her career, Taiyō's anti-aircraft armament was upgraded several times. On 18 August 1944 off Cape Bolinao, Luzon, while escorting a convoy headed for Manila, Taiyō was hit by a torpedo fired by the submarine USS Rasher (SS-269). The hit caused the carrier’s avgas and oil tanks to explode, and Taiyō sank in a mere 26 minutes, with few survivors.