increased number of samurai they now had to support, but also to represent the prestige and power of the daimyō, now consolidated into a single castle. Edo castle, expanded by a factor of twenty between roughly 1600 and 1636 after becoming the shogunal seat. Though obviously something of an exception, the shōgun not being a regular daimyō, it nevertheless serves as a fine example of these developments. These vastly consolidated and expanded castles, and the great number of samurai living, by necessity, in and around them, thus led to an explosion in urban growth in 17th century Japan. As contact with Western powers increased in the middle of the 19th century, some castles such as Goryōkaku in Hokkaidō were turned once again to martial purposes. No longer needed to resist samurai cavalry charges, or arquebus squads, attempts were made to convert Goryōkaku, and a handful of other castles across the country, into defensible positions against the cannon of Western naval vessels. Modern period Meiji Restoration Before the feudal system could be completely overturned, castles played a role in the initial resistance to the Meiji Restoration. In January 1868, the Boshin War broke out in Kyoto, between samurai forces loyal to the disaffected Bakufu government, and allied forces loyal to the new Meiji Emperor, which consisted mainly of samurai and rōnin from the Choshu and Satsuma domains. By January 31, the Bakufu army had retreated to Osaka Castle in disarray and the shōgun, Tokugawa Yoshinobu had fled to Edo (later Tokyo). Osaka Castle was surrendered to the Imperial forces without a fight, and on February 3, 1868, Osaka Castle was burned. The destruction of Osaka Castle, which was a significant symbol of the power of the Shogun in western Japan, dealt a major blow to the prestige of the shogunate and the morale of their troops. From Edo, the Bakufu forces fled north to the Aizu domain, from whence a large number of their troops hailed. As the Aizu Campaign opened, Nagaoka and Komine Castles were the scenes of heavy fighting. In the course of battle, Komine Castle was burned (it was re-built in 1994). The allied forces continued north to the city of Wakamatsu, and lay siege to Tsuruga Castle. After a month, with the walls and main tower pock-marked by bullets and cannonballs, Tsuruga Castle was finally surrendered. It was later demolished and not re-built until 1965. From Aizu,