When Edo Castle was relinquished to the new government army, ENOMOTO, dissatisfied with the way the new government was treating the Tokugawa Family, led the former bakufu fleet composed of eight warships, Kaiyo, Kaiten Maru, Banryu Maru, Chiyodagata Maru, Shinsokumaru, Mikaho Maru, Kanrin Maru and Chogei Maru, with the other former shogun's retainers of the resistance force.
新政府軍が江戸開城すると、徳川家に対する政府の処置を不満とし榎本は抗戦派の旧幕臣とともに開陽、回天丸、蟠竜丸、千代田形丸、神速丸、美嘉保丸、咸臨丸、長鯨丸の8艦から成る旧幕府艦隊を率いて脱出する。