After the death of the eighth regent Tokimune HOJO, the senior vassal Yasumori ADACHI and TAIRA no Yoritsune, Uchi-Kanrei (head of Tokuso Family [the patrimonial head of the main branch of the Hojo clan]) opposed each other and Yasumori, his family, and his party were destroyed in this incident in which Yoritsuna's party made the preemptive attack.
8代執権北条時宗の死後、有力御家人の安達泰盛と、内管領の平頼綱が対立し、頼綱方の先制攻撃を受けた泰盛とその一族・与党が滅ぼされた事件である。