List of battleships of Japan

Between the 1890s and 1940s, the Imperial Japanese Navy (IJN) built a series of battleships as it expanded its fleet. Previously, the Empire of Japan had acquired a few ironclad warships from foreign builders, although it had adopted the Jeune École naval doctrine which emphasized cheap torpedo boats and commerce raiding to offset expensive, heavily armored ships. To counter the Imperial Chinese Beiyang Fleet in the early 1890s, however, Japan ordered two Fuji-class battleships from Great Britain as Japan lacked the technology and capability to construct its own vessels. Combat experience in the First Sino-Japanese War of 1894–1895 convinced the IJN that its doctrine was untenable, leading to a ten-year naval construction program that called for a total of six battleships and six armored cruisers (the Six-Six Fleet). The two ships of the Shikishima class and the battleships Asahi and Mikasa were also purchased from Great Britain. Aware that they could not outbuild the Americans or British, the IJN decided that their ships would always be qualitatively superior to offset their quantitative inferiority.^[1]

To counter reinforcement of the Russian Empire's Pacific Squadron as tensions rose between the Russians and the Japanese over control of Korea and Manchuria in the early 1900s, Japan ordered the two battleships of the Katori class in 1903, the last battleships ordered from abroad.^[2] To preempt further reinforcements before their own ships were completed, they began the Russo-Japanese War in 1904 with a surprise attack on the Russian base at Port Arthur. Shortly after the war began, the IJN ordered the two ships of the Satsuma class, the first battleships to be built in Japan.^[3] The Imperial Japanese Army captured Port Arthur, along with the surviving ships of the Pacific Squadron by the end of the year. The Russians had dispatched the bulk of their Baltic Fleet to relieve Port Arthur, which reached the Korea Strait in May 1905 and was virtually annihilated by the IJN in the Battle of Tsushima.^[4] During the war, Japan captured a total of five Russian pre-dreadnought battleships. They were repaired and commissioned into the Japanese fleet, two of which were later sold back to Russia during World War I, as the two countries were by then allies. The magnitude of the victory at Tsushima caused the leadership of the IJN to believe that a surface engagement between the main fleets was the only decisive battle in modern warfare and would be decided by battleships armed with the largest guns.^[5]

After the war, the Japanese Empire immediately turned its focus to the two remaining rivals for imperial dominance in the Pacific Ocean, Britain and the United States,^[6] believing that conflict would inevitably arise between Japan and at least one of its two main rivals. Accordingly, the 1907 Imperial Defense Policy called for the construction of a battle fleet of eight modern battleships and eight battlecruisers.^[7] This was the genesis of the Eight-Eight Fleet Program, the development of a cohesive battle line of sixteen capital ships.^[8] The launch of HMS Dreadnought in 1906 and the battlecruiser Invincible the following year by the Royal Navy raised the stakes^[9] and complicated Japan's plans as they rendered all existing battleships and armored cruisers obsolete, forcing Japan to restart the Eight-Eight plan with dreadnought battleships and battlecruisers.^[10][11] This began with the Kawachi class in 1907, followed by the Fusō and Ise classes in the 1910s. Japan ordered its seventh and eighth dreadnoughts with the Nagato class in 1916 and 1917.^[12]

In 1919, American President Woodrow Wilson announced the resumption of the 1916 naval construction program and the Japanese ordered eight fast battleships of the Kii and Number 13 classes in response.^[13] The prospect of a new massively expensive arms race between the United States, Britain and Japan after the war caused the three powers to agree to the Washington Naval Treaty which limited Japan to a ratio of 3:5:5 in battleship tonnage to the United States and Britain. The treaty forced the IJN to dispose of all of its pre-dreadnoughts and the oldest dreadnoughts; the ships then under construction had to be broken up or sunk as targets. Furthermore, the treaty mandated a building holiday that barred the construction of new battleships for ten years. During this period, opponents of the Washington Naval Treaty and its successors had taken control of the upper echelons of the IJN^[14] and rebuilt the Kongō-class battlecruisers into fast battleships and modernized the existing ships.^[15] Coupled with the growth of ultranationalism and dominance of the government by the military, the government decided to withdraw from the treaty regime when it expired in 1936. Planning by the Navy General Staff for the post-treaty era began in 1934 and included five large battleships armed with nine 460 mm (18.1 in) guns; these ships became the Yamato class.^[16] While the Yamatos were under construction in the late 1930s, the IJN began designing a successor class, the Design A-150 armed with 51 cm (20.1 in) guns, but never laid any down as they prepared for war and other ships had higher priority.^[17]