Yoshimori joined this and when Yasuhira and the FUJIWARA no Kunihira brothers ran away after their huge defeat at the Battle of Atsukashiyama, Yoshimori chased them at the vanguard and fought an arrow battle against Kunihira.
義盛はこれに従軍し、阿津賀志山の戦いで泰衡・藤原国衡兄弟は大敗を喫し逃亡、義盛は先陣をきってこれを追撃し、国衡と矢戦を交わした。