 Based on the ship "Minerva" of the French Oriental Fleet, he deserted when the ship was anchored at Yokohama harbour, with his friend Henri Nicol to rally other French officers, led by Jules Brunet, who had embraced the cause of the Bakufu in the Boshin War.On 29 November 1868, Eugène Collache and Nicol left Yokohama on board a commercial ship, the "Sophie-Hélène", chartered by a Swiss businessman.The two French officers first reached in the province of Nanbu (modern Miyagi Prefecture), where they learned that the Imperial forces had subdued the "daimyōs" of Northern Japan, and that the rebel forces favorable to the "shōgun" had fled to the island of Hokkaidō.