Sima Yue
In 306, as the War of the Eight Princes neared its end and Emperor Hui was allowed to return to Luoyang after Sima Yue the Prince of Donghai defeated Sima Yong, he welcomed Yang back as his empress. In early 307, however, he was poisoned to death. (Most historians believe that Sima Yue was behind the poisoning, but there is no conclusive evidence.) The recognized heir was Emperor Hui's brother, Sima Chi the crown prince, but Empress Yang, believing that she would not be honored as empress dowager if her brother-in-law inherited the throne, tried to have Sima Qin declared emperor; she was rebuffed by Sima Yue, however, and Crown Prince Chi succeeded to the throne as Emperor Huai. (Her attempt might have cost Prince Qin his life, as Sima Yue had him executed in 308.) Emperor Huai honored her with the title "Empress Hui," but not empress dowager.