Since the beginning of the seventeenth century, the Tokugawa shogunate ruling Japan pursued a policy of
isolating the country from outside influences. Foreign trade was maintained only with the
Dutch and the
Chinese and was conducted exclusively at
Nagasaki under a strict government monopoly. No foreigners were allowed to set foot in Japan, and no Japanese was permitted to travel abroad. In June 1635 a law was proclaimed prohibiting the construction of large, ocean-capable vessels. However, by the early nineteenth century, this policy of isolation was increasingly under challenge. In 1846, an official American expedition led by Commodore
James Biddle on an official mission with two ships, including one warship armed with 72 cannons, asking for ports to be opened for trade, but his requests for a trade agreement were refused. Following the
July 1853 visit of
Commodore Perry, an intense debate erupted within the Japanese government on how to handle the unprecedented threat to the nation's capital, and the only universal consensus was that steps be taken immediately to bolster Japan's coastal defenses. The law forbidding construction of large vessels was repealed, and many of the
feudal domains took immediate steps to construct or purchase warships. These included the
Hōō Maru constructed by the
Uraga bugyō office, and the
Shōhei Maru constructed by
Satsuma Domain. The former
daimyō of Mito Domain,
Mito Nariaki was regarded as one of the foremost experts on military matters within the Japanese government, and was a strong proponent of
rangaku studies to acquire military technology from the European powers. The domain had already experiments with small, western-based designs in the 1840s in secret. In December 1853, the domain received official authority from Shōgun
Tokugawa Iesada to construct a large warship, based on designs and reverse-engineering from textbooks and reference materials acquired from the Dutch. The new vessel was launched in 1855 with some difficulty, and was named and commissioned into service in June 1856. ==Design==