Battle of Aizu
Due to Hijikata being incapacitated as a result of the injuries sustained at the Battle of Utsunomiya Castle in May 1868, the Kōyō Chinbutai fought in defense of Aizu territory under Saitō Hajime in the Battle of Shirakawa in June 1868. After the Battle of Bonari Pass in October 1868, when Hijikata decided to retreat from Aizu, Saitō and a small group of Shinsengumi parted with Hijikata and continued to fight with the Aizu army until the very end of the Battle of Aizu.