Sima Lun

Sima Lun (traditional Chinese: 司馬倫; simplified Chinese: 司马伦; pinyin: Sīmǎ Lún; Wade–Giles: Ssu-ma Lun) (born before 250 – poisoned 5 June 301), courtesy name Ziyi (子彛), was titled the Prince of Zhao (趙王; 赵王; Zhào Wáng) and the usurper of the Jin dynasty from 3 February to 31 May 301. He is usually not counted in the list of Jin emperors due to his brief reign and was often mentioned by historians as a usurper. He was the third of the eight princes commonly associated with the War of the Eight Princes.

A son of Sima Yi, Sima Lun was arguably the most reviled and hated among the Eight Princes. His tenure as governor in the Guanzhong region ended in a large-scale rebellion by the local tribes which forced him to be recalled back to the capital, Luoyang in 296. Back in the capital, he became a confidant of Empress Jia and her family, who ruled the empire behind the throne of her husband and Sima Lun's grandnephew, Emperor Hui. As she lost support due to her controversial removal of the Crown Prince, Sima Yu, Sima Lun led a coup to depose her and installed himself as the emperor's new regent. Sima Lun, with the help of his advisor, Sun Xiu had all his court rivals brutally purged and eventually compelled Emperor Hui to abdicate the throne to him in 301. His usurpation was immediately denounced, and just a few months later, he was defeated by the coalition of the "Three Princes" (Sima Jiong, Sima Ying and Sima Yong) and forced to commit suicide.

Sima Lun's usurpation was the beginning of a more destructive chapter in the War of the Eight Princes. No longer confined within the walls of Luoyang, the conflict had escalated into a series of full-blown civil wars that would devastate northern China for years to come.