When the former bakufu kaigun was defeated in the Battle of Toba-Fushimi, Yoshinobu TOKUGAWA, who stayed in Osaka-jo Castle, boarded 'kaiyomaru' to Edo, without permission from Shogun's retainer of war party, and they moved to Edo.
鳥羽伏見の戦いで旧幕府軍が敗北すると、大坂城にいた徳川慶喜らは、主戦派の幕臣に無断で旗艦「開陽丸」に乗って江戸へ引き揚げたため、江戸に移った。