Ouetsu Reppan Domei

Ōuetsu Reppan Dōmei

奥羽越列藩同盟
Standard-bearer in 2006 Aizu parade bearing the flag of the Ōuetsu Reppan Dōmei
Formation	Spring 1868
Type	Military and political alliance
Headquarters	Shiroishi, Sendai Domain, Japan
Membership	31 domains of Northern Japan
Official language	Japanese
Meishu (Alliance Head)	Prince Kitashirakawa Yoshihisa
Sotoku (Governor-General)	Date Yoshikuni, Uesugi Narinori

The Ōuetsu Reppan Dōmei (奥羽越列藩同盟^?, Alliance of the domains of Mutsu, Dewa, and Echigo) was a Japanese military-political coalition established and disestablished over the course of several months in early to mid-1868 during the Boshin War. Its flag was either a white interwoven five-pointed star on a black field, or a black interwoven five-pointed star on a white field. It is also known as the Northern Alliance (北部同盟, Hokubu Doumei^?).

The Alliance centered on the Sendai, Yonezawa, and Nihonmatsu domains, and drew together nearly all domains from the provinces of Mutsu and Dewa, several domains of northern Echigo Province, and even the Matsumae Domain of Ezo (modern-day Hokkaidō). Headquartered at Shiroishi Castle, the alliance's nominal head was Prince Kitashirakawa Yoshihisa, the onetime abbot of Kan'eiji Temple in Edo who fled north following the Satsuma–Chōshū takeover of the city, who declared himself "Emperor Tobu", with Date Yoshikuni of Sendai and Uesugi Narinori of Yonezawa as the head of the Alliance. Although heteroclitic in nature, the Alliance formed of a combination of modern and traditional forces, and mobilized a total of about 50,000 soldiers. Though the alliance did its best to support the Aizu domain (会津藩), Aizu was not formally part of the alliance "Kaishō Alliance" (会庄同盟); neither was Shōnai (庄内藩).