Yokosuka Naval District

Yokosuka Naval District (横須賀鎮守府, Yokosuka chinjufu^?) was the first of four main administrative districts of the pre-war Imperial Japanese Navy. Its territory included Tokyo Bay and the Pacific coasts of central and northern Honshū from the Kii Peninsula to Shimokita Peninsula. Its headquarters, along with most of its installations, including the Yokosuka Naval Arsenal, were located in the city of Yokosuka, which constituted the Yokosuka Naval Base.

The location of Yokosuka at the entrance to strategic Tokyo Bay was recognized of critical importance by the Tokugawa shogunate and early Meiji government. In 1866, the Tokugawa shogunate government established the Yokosuka Seisakusho, a military arsenal and naval base, with the help of foreign engineers, including the French naval architect Léonce Verny. The new facility was intended to produce modern, western-style warships and equipment for the Tokugawa navy. After the Boshin War and the Meiji Restoration, the new Meiji government took over control of the facility in 1871, renaming it the Yokosuka Zosenjo (Yokosuka Shipyards). In August 1876, the Imperial Japanese Navy was organized into eastern and a western strategic zones, with the eastern zone Tōkai chinjufu (東海鎮守府^?) based at Yokosuka, and the western zone Saikai chinjufu (西海鎮守府^?) based at Nagasaki. However, for ease of communications with naval headquarters in Tokyo, the Tōkai Naval District was relocated to Yokohama in September 1876.

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