Japanese aircraft carrier Hiyō

Hiyo: The Tale of a Japanese Aircraft Carrier

Imagine a ship that could transform from a luxurious ocean liner into a formidable aircraft carrier, ready to face the challenges of World War II. That was Hiyo, the pride of the Imperial Japanese Navy.

The Birth of an Aircraft Carrier

Originally planned as the ocean liner Izumo Maru, Hiyo’s journey began in 1939 when she was laid down. It wasn’t until February 1941 that she was purchased by the Navy Ministry and temporarily referred to as No. 1002 Ship (Dai 1002 bankan) to keep her conversion a secret. The ship’s transformation from a luxury liner to an aircraft carrier was nothing short of remarkable, showcasing the ingenuity and adaptability of naval engineering during wartime.

Aircraft Carrier Specifications

Hiyo was designed with a length of 220 meters overall, displacing 24,150 tonnes at standard load. Her flight deck stretched an impressive 210.3 meters and featured two superimposed hangars that could be subdivided by four fire curtains. This design allowed for efficient storage and operation of aircraft, a crucial aspect in the dynamic environment of naval warfare.

Armament and Defense

The primary armament consisted of twelve 12.7-centimeter Type 89 dual-purpose guns in twin mounts on sponsons along the sides of the hull. Additionally, Hiyo was equipped with eight triple mounts for 2.5 centimeter Type 96 light AA guns alongside the flight deck, later increased to twelve single mounts and four more triple mounts added in early 1943. These defenses were essential in protecting the carrier from enemy attacks.

Operational History

Hiyo’s operational history is a testament to her versatility and resilience. She participated in the Guadalcanal campaign, missed the Battle of the Santa Cruz Islands due to an electrical generator fire, and spent three months under repair before returning to combat. Her air group initially consisted of 12 Mitsubishi A5M ‘Claude’ fighters, plus four in storage, 18 Aichi D3A ‘Val’ dive bombers, plus two in storage, and 18 Nakajima B5N ‘Kate’ torpedo bombers.

Revisions and Adjustments

By the time Hiyo was commissioned in 1942, her air group had been revised to substitute a dozen Mitsubishi A6M Zero fighters and three in storage for the A5Ms. As lessons from the Battle of Midway were applied, the fighter complement was increased to 21 Zeros, while the B5Ns were reduced to nine. This adjustment reflected the evolving tactics and strategies employed by the Japanese Navy.

Final Days

The final months of Hiyo’s life were marked by continuous operations and repairs. She was torpedoed in mid-1943 and spent most of the next six months training and ferrying aircraft before returning to combat. However, her fate was sealed during the Battle of the Philippine Sea on June 20, 1944. A gasoline-vapour explosion caused by an American torpedo hit resulted in the loss of 247 officers and ratings.

Conclusion

Hiyo’s story is a poignant reminder of the challenges faced by naval forces during World War II. From her transformation from a luxury liner to a formidable aircraft carrier, through her active service, to her final moments, Hiyo embodied the spirit and resilience of the Imperial Japanese Navy.