The fleet arrived at Washinoki in the north of Hakodate on October 20, and the Battle of Hakodate began. The next day, the ship visited the Hakodate Port with thir consort ship "Banryu Maru", and on the 25th, troops and sailors of the Bakufu Army landed on the island and occupied each cities from Imperial Japanese troops. On the 27th, the Akita clan warship "Kaohsiung Maru", which did not know about it, arrived at the port, so Gengo had his fellow officers of both "Kaiten Maru" and "Banryu Maru," lead a group of sailors and captured the Imperial ships, including the ironclad "". In a battle with soldiers of the Matsumae clan (who had sworn their allegiance to the new government), Gengo supported the Bakufu Army, and when the "Kaiyo Maru" sailed around in Esashi, he went to rescue them, but he couldn't save it at last. After many ships where destroyed by the modernized navy, "Kaiten Maru" became the last flagship of the Shogunate Navy.