Enshin fought against its advance team composed of the Ito clan at Mitsuishi-jo Castle; the leader Koremure ITO, who came to heel, remained at Mitsuishi-jo Castle as the reserve force of Saigoku bakufu (Japanese feudal government headed by a shogun); Enshin started toward the east.
しかし、その先発隊である伊東氏と三石城で戦いその盟主である伊藤惟群を服従させ、これを西国幕府軍の備えとして三石城に残し東上を開始した。