蝦夷共和國
In March 1869, "Kasuga Maru" participated in the expedition against the last remnants of the pro-Tokugawa forces in Hokkaido, where they had formed the Republic of Ezo with the support of a few French military advisors such as Jules Brunet. While at Miyako Bay, the expedition suffered a surprise attack by the Bakufu ship . "Kaiten" attacked the state-of-the art ironclad ship , but she was repulsed by Gatling guns on board the "Kōtetsu" and cannon response by "Kasuga Maru". The encounter has been named the Naval Battle of Miyako Bay. After these events "Kasuga Maru" participated in the Naval Battle of Hakodate Bay in May 1869, until the surrender of the last forces of the Republic of Ezo.