Establishment of Sasebo Naval Arsenal (1903)

In 1886 the Navy decided to develop Sasebo, along with Kure, as a naval port. When the Sasebo Naval District opened in 1889, a shipbuilding department for ship repair was set up and a dry dock built; by 1897, equipment and facilities for ship production had been added, creating the 'Sasebo Shipyards'. The Naval Arsenal Ordinance of 5 November 1903 merged the naval shipyards and ordnance works at each port and created naval arsenals at Yokosuka, Kure, Sasebo and Maizuru; the Sasebo Naval Arsenal was thus formally established in November 1903, responsible for building and repairing warships and weapons and for storing ordnance.

Sasebo was the naval port closest to the Asian continent and the Korean peninsula, and the arsenal kept expanding after the Russo-Japanese War. In 1913, a 250-ton cantilever crane ordered from Britain was installed, enabling the fitting-out of large warships; a large mooring basin was completed in 1916, and Dock No. 7, able to take a Yamato-class battleship, in 1941. New construction centred on light cruisers, destroyers and submarines, including the light cruisers Tatsuta, Kuma, Yubari, Agano and Yahagi; no battleships or heavy cruisers were built there, but the arsenal carried out much fitting-out and conversion work, including on the carriers Akagi and Kaga. The earlier text of this record said it served as a repair facility for the battleships Yamato and Musashi; according to Japanese Wikipedia, the only Yamato-class docking in Dock No. 7 was a single visit by Musashi.

At its World War II peak, the arsenal employed approximately 50,000 workers (the MIC page says the workforce was 'reported to have exceeded 50,000'), among them many mobilised students and conscripted labourers, constructing destroyers, light cruisers, submarines, and other vessels. The great air raid of 28-29 June 1945 burned the city, but the port and arsenal suffered comparatively light damage.

The arsenal was abolished after the defeat and its facilities taken over by the occupation forces. Sasebo Ship Industry Co. (SSK), founded in 1946, began operating in leased arsenal land and facilities; it was renamed Sasebo Heavy Industries in 1961 and acquired the property. The former arsenal site is now divided among US Fleet Activities Sasebo, the Japan Maritime Self-Defense Force and Sasebo Heavy Industries, and the 250-ton crane and several Meiji- and Taisho-period docks are still in use. In 2016 Sasebo's former naval facilities were recognised as part of the Japan Heritage story of the four naval districts (Yokosuka, Kure, Sasebo and Maizuru).