In July 1205, because of the plot by Tokimasa HOJO, Shigetada HATAKEYAMA was suspected of planning a rebellion, an army to kill him was formed with Tokimasa's legitimate son Yoshitoki as the supreme commander; and Yoshimori was there as the sole Taishogun (commander in chief), and before the large Shogunal army, Shigetada and his family were destroyed (Shigetada HATAKEYAMA Rebellion).
元久2年（1205年）6月、北条時政の策謀により畠山重忠に謀反の疑いがかけられ、時政の嫡男の義時を総大将とする討伐の軍が発せられ、義盛も一手の大将軍として出陣、幕府の大軍を前に重忠とその一族は滅ぼされた（畠山重忠の乱）。