On September 20, 1868 the pro-Shōgunate Ōuetsu Reppan Dōmei was proclaimed at Morioka, capital of the Nambu clan who rule Morioka Domain. The territory of the Nambu extended along the northeastern half of Mutsu Province, as far north as Shimokita Peninsula, and the Nambu controlled a subsidiary domain at Hachinohe. The northeast of Mutsu Province was dominated by the Nambu clan's hereditary rivals, the Tsugaru clan of Hirosaki Domain, with a subsidiary domain at Kuroishi.