On July 4, 1868, the Satsuma army led by Saigo defeated Shogitai (a group of the former Tokugawa retainers opposed to the Meiji government who fought in the Battle of Ueno) in the Ueno War but the Aizu Clan continued to fight back while various clans in the Tohoku region formed the Ouetsu-reppan alliance.
1868年（慶応4年）5月15日(旧暦)、西郷が率いる薩軍は上野戦争で彰義隊を破ったが、会津藩は抗戦を続け、東北諸藩は奥羽越列藩同盟を結んだ。