List of battlecruisers of Japan

The Imperial Japanese Navy (大日本帝国海軍) built four battlecruisers, with plans for an additional four, during the first decades of the 20th century. The battlecruiser was an outgrowth of the armoured cruiser concept, which had proved highly successful against the Russian Baltic Fleet in the Battle of Tsushima at the end of the Russo-Japanese War. In the aftermath, the Japanese immediately turned their focus to the two remaining rivals for imperial dominance in the Pacific Ocean: Britain and the United States.^[1] Japanese naval planners calculated that in any conflict with the U.S. Navy, Japan would need a fleet at least 70 percent as strong as the United States' in order to emerge victorious. To that end, the concept of the Eight-Eight fleet was developed, where eight battleships and eight battlecruisers would form a cohesive battle line.^[2] Similar to the German Imperial Navy (Kaiserliche Marine) and in contrast to the Royal Navy,^[3] the Japanese envisioned and designed battlecruisers that could operate alongside more heavily armoured battleships to counter numerical superiority.^[4]

The first phase of the Eight-Eight plan began in 1910, when the Diet of Japan authorised the construction of one battleship (Fusō) and four battlecruisers of the Kongō class. Designed by British naval architect George Thurston, the first of these battlecruisers (Kongō) was constructed in Britain by Vickers, while the remaining three were constructed in Japan. Armed with eight 14-inch (360 mm) guns and with a top speed of 30 knots (35 mph; 56 km/h), they were the most advanced capital ships of their time.^[5] At the height of the First World War, an additional four battlecruisers of the Amagi class were ordered. The ships would have had a main battery of ten 16-inch (410 mm) guns, but none were ever completed as battlecruisers, as the Washington Naval Treaty limited the size of the navies of Japan, Britain and the United States.^[6] Before the Second World War, a further class of two battlecruisers were planned (Design B-65), but more pressing naval priorities and a faltering war effort ensured these ships never reached the construction phase.^[7]

Of the eight battlecruiser hulls laid down by Japan (the four Kongō and four Amagi class), none survived the Second World War. Amagi was being converted to an aircraft carrier when its hull was catastrophically damaged by the Great Kantō earthquake in 1923 and subsequently broken up, while the last two of the Amagi class were scrapped in 1924 according to the terms of the Washington Treaty.^[6] Akagi was converted to an aircraft carrier in the 1920s, but was scuttled after suffering severe damage from air attacks during the Battle of Midway on 5 June 1942. The four Kongō-class ships were lost in action as well: two during the Naval Battle of Guadalcanal in November 1942,^[8] one by American submarine in November 1944,^[9] and one by American aircraft at Kure Naval Base in July 1945.^[10]