Sima Liang
In 289, as Emperor Wu neared death, he considered whom to make the regent for Crown Prince Zhong. He considered both Empress Yang's father Yang Jun and his uncle Sima Liang the Prince of Ru'nan, the most respected of the imperial princes. As a result, Yang Jun became fearful of Sima Liang and had him posted to the key city of Xuchang (許昌, in modern Xuchang, Henan). By 290, Emperor Wu resolved to let Yang and Sima Liang both be regents, but after he wrote his will, the will was seized by Yang Jun, who instead had another will promulgated in which Yang alone was named regent. Emperor Wu died soon thereafter, and Crown Prince Zhong ascended the throne as Emperor Hui. Crown Princess Jia became empress, and Prince Yu became crown prince.