Following text peeled shamelessly from Wikipedia:
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. The construction of the arsenal was an important first step for the modernization of Japan's industry. Modern buildings, an aqueduct, foundry, brick factories, technical schools to train Japanese technicians were established.
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). The first dry dock was opened in 1871, and is still in operation today. Japan's first domestically produced warship, Saiki, was completed the same year.