Battle of Miyako Bay The was a naval action on 6 May 1869 . It was part of the overall Battle of Hakodate at the end of the Boshin War , a civil war in Japan between Imperial forces of the new government , and samurai rebels that wanted to maintain the feudal caste system . Preparations . After the remnants of the " Bakufu " army loyal to the former Tokugawa shogunate refused to surrender to the new Meiji government in the Battle of Ueno and Battle of Aizu , they fled north to occupy the island of Hokkaidō and established the Republic of Ezo . The navy of the Imperial forces also moved north to support the eventual invasion of Hokkaidō . The Imperial navy departed Tokyo on 9 March 1869 , and reached the harbor of Miyako , north of Sendai , on 20 March . The government fleet had been rapidly constituted around the French - built ironclad warship " Kōtetsu " , which had been purchased from the United States . Other ships included " Kasuga " , " Hiryū " , " Teibo " , " Yoshun " , and " Moshun " , which had been supplied by the domains of Saga , Chōshū and Satsuma to the new central government in 1868 . There were altogether eight Imperial ships : " Kōtetsu " , " Kasuga " , 3 small corvette s and 3 transport ships . Anticipating the arrival of the Imperial fleet , the rebels organized a plan to seize the revolutionary new warship " Kōtetsu " , and dispatched three warships for a surprise attack : The ships encountered bad weather , in which " Takao " suffered from engine trouble , and " Banryu " became separated . " Banryu " eventually returned to Hokkaidō , without joining the battle . Action . To create surprise , " Kaiten " planned to enter Miyako harbor under an American flag . Unable to achieve more than due to engine trouble , " Takao " trailed behind , and " Kaiten " first joined battle . " Kaiten " approached the enemy ships and raised the Republic of Ezo flag seconds before boarding " Kōtetsu " . She rammed her prow into the side of " Kōtetsu " , and started firing her guns . Her deck however proved higher than that of " Kōtetsu " by close to three meters , forcing the samurai to jump one by one in a trickle . After the first surprise passed , " Kōtetsu " managed to repel the attack with a Gatling gun , causing huge losses to the attackers . Most of the attacking samurai perished ; Nicol was hit by two bullets , and boarding party commander Koga Gengo was killed and his position taken over by Admiral Arai Ikunosuke . In the action , " Kaiten " damaged three enemy warships , but finally disengaged without having captured " Kōtetsu " . " Kaiten " steamed out of Miyako Bay pursued by the Imperial fleet ( which had been warming up their engines even before the attack began ) , just as " Takao " was entering . " Kaiten " eventually escaped to Hokkaidō , but " Takao " was too slow to outdistance its pursuers and was beached at little distance from Miyako Bay , so that her crew could escape inland , and was scuttled by explosion . The 40 crewmen ( including 30 samurai and the ex - French officer Eugène Collache ) managed to flee for a few days , but finally surrendered to government forces . They were brought to Tokyo for imprisonment and trial . Although the fate of the Japanese rebels is unknown , Collache was eventually pardoned and deported back to France . Conclusion . The Naval Battle of Miyako was a daring but desperate attempt by the Republic of Ezo forces to neutralize the powerful " Kōtetsu " . It was the first case of an " abordage " ( boarding ) maneuver in Japan . Although the attempt ended in failure , the loss of the " Takao " was marginal . The Imperial Navy continued north unimpeded , and supported landing and combat operations of thousands of government troops in the Battle of Hakodate .