After the overthrow of the Tokugawa shogunate (bakufu) in the Boshin War by the Meiji Restoration, a part of the former shōgun's navy, led by Admiral Enomoto Takeaki, retreated from the capital Edo (Tokyo) in October 1868, sailing north to continue the fight against the advancing Imperial army.

After one month in Sendai the fleet sailed further north, arriving in Hakodate, Ezo, on 3 December, which was captured five days later by a force of 4,000 shogunate troops.

[6] Enomoto made a last effort to petition the Imperial Court to be allowed to develop Hokkaido and maintain the traditions of the samurai unmolested, but his request was denied.

[10] Votes were cast through open ballots and resulted in the election of Enomoto Takeaki as sosai, an office variously translated as president or director-general, and Matsudaira Tarō as fuku-sosai (vice-president or assistant governor-general).

[citation needed] The treasury included 180,000 gold ryō coins Enomoto retrieved from Osaka Castle following shōgun Tokugawa Yoshinobu's precipitous departure after the Battle of Toba–Fushimi in early 1868.

The land force was organised under a joint Franco-Japanese command, commander-in-chief Ōtori Keisuke being seconded by the French captain Jules Brunet.

The simple Japanese are puppets whom he manipulates with great skill... he has carried out a veritable 1789 French Revolution in this brave new Japan; the election of leaders and the determination of rank by merit and not birth—these are fabulous things for this country, and he has been able to do things very well, considering the seriousness of the situation...[16]Imperial troops soon consolidated their hold on mainland Japan, and in April 1869 dispatched a fleet and an infantry force of 7,000 men to Hokkaido.

We pray that this portion of the Empire may be conferred upon our late lord, Tokugawa Kamenosuke; and in that case, we shall repay your beneficence by our faithful guardianship of the northern gate.