Shortly after the war began, the IJN ordered the two ships of the Satsuma class, the first battleships to be built in Japan. 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. 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.

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. The two ships of the Shikishima class and the battleships Asahi and Mikasa were also purchased from Great Britain. 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). 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. 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. Between the 1890s and 1940s, the Imperial Japanese Navy (IJN) built a series of battleships as it expanded its fleet.

Cost of musashi world warships