Sima Yi
In 249, during the reign of Cao Rui's successor, Cao Fang, the regent Sima Yi seized state power from his co-regent, Cao Shuang, in a coup. This event marked the collapse of imperial authority in Wei, as Cao Fang's role had been reduced to a puppet ruler while Sima Yi wielded state power firmly in his hands. Wang Ling, a Wei general, tried to rebel against Sima Yi, but was swiftly dealt with, and took his own life. Sima Yi died on 7 September 251, passing on his authority to his eldest son, Sima Shi, who continued ruling as regent.