Sima Yi

Sima Yi began his political career in 208 under Cao Cao and rose quickly through military and domestic success: repelling invasions from Shu and Wu, crushing Meng Da's Xincheng Rebellion, and conquering Liaodong. Between 231 and 234 he became known for defending Wei from repeated Shu invasions. Made co-regent in 239 for the young emperor Cao Fang, he watched his counterpart Cao Shuang grow corrupt and attempt to sideline him. In February 249 Sima Yi struck: a carefully planned coup that ended with Cao Shuang and his circle executed. He became the singular authority in Wei, controlling civil officials and military commanders alike, silencing opposition and placing the imperial Cao clan under surveillance in Ye City. From 249 until his death on 7 September 251, chronic illness kept him from court; instead the emperor visited his private estate, where Sima Yi ran the state through his own administrative apparatus. His sons Sima Shi and Sima Zhao expanded that grip until his grandson Sima Yan founded the Jin dynasty in 266, naming Sima Yi its first emperor posthumously.