The resignation of Seikan-ha (supporters of sending army to Korea) Sangi (councilors), including Takamori SAIGO, Shinpei ETO and Taisuke ITAGAI, who were defeated at the Seikan Ronsou (debate on subjugation of Korea) occured in October 1873, made fuhei shizoku (former samurai with gripes) even more frustrated since they looked forward to conquer Korea.
前年明治6年（1873年）10月に政府内で起きたいわゆる征韓論争に敗れた征韓派参議の西郷隆盛・江藤新平・板垣退助らが下野したことは、征韓論に期するところのあった不平士族らにとって、いっそうの不満を高めることとなった。