In 260, Cao Mao, not being able to make much headway in his attempt to reduce Sima Zhao's hold on power, tried to start a "coup d'état" himself with the imperial guards loyal to him, and after initial successes near the palace, was nevertheless killed in battle. Empress Dowager Guo was forced to issue an edict posthumously deposing him. This time, further, Sima Zhao would completely ignore Empress Dowager Guo's wishes in determining Cao Mao's successor, and he made Cao Huan, the Duke of Changdao District, a grandson of Cao Cao, emperor, even though Cao Rui's brothers still had issue. She died in February 264 without being able to make any further impact against the power of the Simas, and Sima Zhao's son Sima Yan eventually usurped the throne in early 266 and established the Jin dynasty. She was buried on 13 April 264.