page_title: Japanese battleship Tosa
section_title: Design and construction
hierarchical_section_title: Japanese battleship Tosa / Design and construction
caption_attribution_description: English: Imperial Japanese Navy battleship Tosa launched from Nagasaki shipyard.
context_page_description: Tosa was a planned battleship of the Imperial Japanese Navy. Designed by Yuzuru Hiraga, she was envisioned as the lead ship of the Tosa class of two 39,900-long-ton ships. The battleships would have been armed with ten 410 mm guns and bring Japan closer to its goal of an "Eight-four" fleet. However, after the Washington Naval Conference and the signing of the Washington Naval Treaty, all work on the ship was halted. With the vessel required to be destroyed in accordance with the terms of the treaty, the incomplete Tosa was then subjected to various tests to gauge the effect of Japanese weaponry before being scuttled on 9 February 1925.
context_section_description: Designed by Yuzuru Hiraga, Tosa was intended to be part of a Japanese "Eight-four fleet", comprising eight battleships and four battlecruisers, the successor to the proposed "Eight-eight fleet". Tosa and her sister ship Kaga were intended to be the second set of high-speed battleships (after the Nagato class) under the plan, and were approved for construction in the Diet's 14 July 1917 warship-building authorization. Engineering blueprints for the two ships were completed by Japanese naval engineers in 1919. Based on Japanese studies of the British experience at the Battle of Jutland, the ships were to include new features over previous designs, including higher steaming speed despite increased tonnage, flush decks, and inclined armor.
  Tosa was laid down on 16 February 1920 by Mitsubishi in Nagasaki. She utilized the same slipway where, two decades later, the Yamato-class battleship Musashi would be built. Tosa was originally scheduled to be launched in October 1921, but multiple strikes delayed it until November. Ultimately, the battleship was not launched until 18 December 1921, two months behind schedule. Fitting-out commenced soon after with a projected completion date of July 1922. However, work on Tosa was halted on 5 February 1922, one day before Japan signed the Washington Naval Treaty. Under the terms of the treaty, construction of Tosa and Kaga was formally canceled on 5 May 1922.
caption: Tosa's launch, 18 December 1921
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