When the Onin War began in Kyoto, triggered by a combination of the matters of the succession of the Ashikaga shogun family, the conflict over the head of the Hatakeyama clan as well as the conflict in the Shiba clan, Yoshitoshi, who joined the eastern army led by Katsumoto HOSOKAWA, disregarded what was happening in Kyoto and quickly achieved military results in Echizen Province.
このような斯波家の内訌に加え、足利将軍家の継嗣問題や、畠山氏の家督争いなどが関係して応仁の乱が起きると、義敏は、細川勝元率いる東軍に属して戦い、京での戦乱を後目に、いち早く越前に下向して戦果を上げようとした。