Sima Rui was born in 276 in the then-Jin capital Luoyang, as the son of Sima Jin the Prince of Langye and his wife Princess Xiahou Wenji . His father died in 290, and he became the Prince of Langye. The ''Book of Jin'' referred to him as steady and dexterious, personality-wise.
In 304, in the midst of the War of the Eight Princes, Sima Rui participated in Sima Yue the Prince of Donghai's campaign against Sima Ying the Prince of Chengdu as a minor general. After Sima Ying defeated Sima Yue, Sima Yue executed Sima Rui's uncle Sima Yao the Prince of Dong'an, which caused Sima Rui much fear. He decided to flee back to his principality Langye , under counsel of Sima Yue's assistant Wang Dao, whom he befriended during the campaign. He first tried to head back to Luoyang, but when he was about to cross the Yellow River, he was stopped by guards instructed to stop any nobles or high level officials from crossing . His own guard Song Dian then arrived and gave him a shove, pretending that they were just construction workers. The guards then allowed them to cross. After Sima Rui got to Luoyang, he took his mother Princess Dowager Xiahou and headed to Langye, where they spent the next few years away from the War of the Eight Princes.
In 307, Sima Yue, who had emerged victorious in the aftermaths of the War of the Eight Princes as the regent for , under the advice of his wife Princess Pei, commissioned Sima Rui as the military commander of parts of Yang Province south of the Yangtze River, with his post at Jianye. Wang Dao became his chief advisor. As Sima Rui lacked fame, after he arrived in Jianye, few of the powerful local gentlemen would come visit and support him. Under Wang Dao's counsel, Sima Rui personally visited He Xun and Gu Rong and invited them to serve in his administration. He and Gu were well-regarded by the local population, which eventually began to trust Sima Rui's leadership. Wang Dao and his cousin, the general Wang Dun, served in key roles, and it was said at the time that the domain was ruled equally by the Simas and the Wangs.
After the fall of Luoyang
In 311, Luoyang fell to Han Zhao forces, and Emperor Huai was captured. A large number of refugees, fleeing Han Zhao forces, crossed the Yangtze River and arrived in Sima Rui's domain. Under Wang Dao's suggestion, Sima Rui sought out the talented men among them and added them to his administration. Meanwhile, he began to exercise more imperial power, and began to put all other provinces south of the Huai River under his own control -- and, for the next few years, under the command of Wang Dun and other generals such as Tao Kan and Zhou Fang , the agrarian rebels resisting Jin rule in Jing and Xiang Provinces were gradually subjugated. However, he made no effort to try to send armies north against Han Zhao. Meanwhile, as his powerful assistants were largely refugees from the north, the native population began to be dissatisfied, and over the next few years there were constant frictions that decreased the effectiveness of Sima Rui's administration. In 315, members of the powerful Zhou clan intended to start an uprising against him, but the conspiracy was exposed by other members of the clan still loyal to Jin, and the conspiracy did not have a major impact. In 315, Wang Dun was finally able to suppress the remaining agrarian rebels in the west, and began to show ambitions and act independently of Sima Rui.
In 313, after Emperor Huai was executed by Han Zhao, Sima Ye, a nephew of Emperor Huai, was declared emperor in Chang'an. Sima Rui was named the Left Prime Minister, a title that he accepted; however, he took no actual actions in aid of the emperor. When his general Zu Ti requested to lead an army north to, he gave Zu only supplies for one thousand men with no actual troops; Zu had to seek out his own soldiers, but was eventually able to recover a number of cities south of the Yellow River.
In 316, Chang'an fell to Han Zhao forces, and Emperor Min was captured. Sima Rui quickly declared that he was going to act against Han Zhao, but then quickly claimed a lack of supplies and cancelled the campaign. In spring 317, his officials requested that he take the throne, and after he declined initially, he took the title "Prince of Jin" -- a title previously used by Sima Zhao while regent of Cao Wei -- rather than emperor. He created his son crown prince.
In early 318, Han Zhao's emperor executed Emperor Min, and three months later, news arrived in Jiankang. Sima Rui then declared himself emperor . At this time, the areas directly under his control were roughly south of the Yellow River and east of the Three Gorges, although pockets of Jin territory in the north -- chief among which was You Province , controlled by the ethnically Xianbei governor Duan Pidi -- largely also recognized him as emperor. However, while technically recognizing him as emperor, Zhang Shi the governor of Liang Province , whose domain would eventually evolve into Former Liang, chose not to use his era names and instead continued to use Emperor Min's era name of Jianxing -- thus hinting non-recognition.
Late in 318, when the Han Zhao emperor Liu Can was overthrown by his official Jin Zhun, Jin Zhun initially indicated that he was submitting to Emperor Yuan's authority, and Emperor Yuan tried to take advantage by sending an army to assist Jin Zhun. However, long before the army could get there, Jin Zhun was defeated by the new Han Zhao emperor Liu Yao and the general Shi Le.
In 319, Duan Pidi's forces collapsed, and he fled to another governor still loyal to Jin -- Shao Xu the governor of Ji Province . However, both Shao and Duan were captured by Shi by 321, ending all resemblance of Jin rule in northern China -- although the Xianbei chief Murong Hui the Duke of Liaodong was still in control of modern Liaoning and still considered himself a Jin vassal.
Confrontation with Wang Dun
By 320, Emperor Yuan's relationship with Wang Dun was at a breaking point, as Wang Dun had grown more and more arrogant and controlling of the western provinces. Emperor Yuan feared him, and therefore began to group men around him who were against Wang Dun as well, such as Liu Huai and Diao Xie -- men of mixed reputation who, in their efforts to suppress the Wangs' power offended many other people. In 321, Emperor Yuan commissioned Dai Yuan and Liu with substantial forces, claiming that they were to defend against Later Zhao attacks, but instead was intending to have them defend against a potential Wang Dun attack.
In spring 322, Wang Dun started his campaign against Emperor Yuan, claiming that Emperor Yuan was being deluded by Liu and Diao, and that his only intent was to clean up the government. He tried to persuade Gan Zhuo , the governor of Liang Province and Sima Cheng the governor of Xiang Province to join him, and while both resisted, neither was effective in their campaigns against his rear guards. Wang quickly arrived in Jiankang, defeating Emperor Yuan's forces and entering and pillaging Jiankang easily. Liu fled to Later Zhao, while Diao, Dai, and Zhou Yi were killed. Emperor Yuan was forced to submit and grant Wang Dun additional powers in the west. Wang Dun, satisfied, allowed Emperor Yuan to remain on the throne, and personally withdrew back to his home base of Wuchang . His forces then defeated and killed Sima Cheng, while a subordinate of Gan's, acting on Wang's orders, assassinated Gan.
After his defeat, Emperor Yuan grew despondent and ill. Around the new year of 323, he died. Crown Prince Shao succeeded to the throne as Emperor Ming.
* ''Jianwu'' 317-318
* ''Taixing'' 318-322
* ''Yongchang'' 322-323
** Sima Jin , the Prince Gong of Langye, son of Sima Zhou Prince Wu of Langye, son of Sima Yi
** Princess Xiahou Yuanji
** Princess Yu Mengmu , posthumoustly honored as Empress Yuanjing
* Major Concubines
** Lady Xun , mother of Crown Prince Shao, Prince Pou, and Princess Xunyang
** Consort Zheng Achun , mother of Princes Huan and Yu, posthumously honored as Empress Dowager Xuan
** Consort Shi, mother of Prince Chong
** Consort Wang, mother of Prince Xi
** Sima Shao , the Crown Prince, later Emperor Ming of Jin
** Sima Pou , initially the Marquess of Changleting, later the Duke of Xuancheng, later Prince Xiao of Langye
** Sima Chong , Prince Ai of Donghai
** Sima Xi , Prince Wei of Wuling
** Sima Huan , initially the Marquess of Changleting, later the Marquess of Xianyiting, later Prince Dao of Langye
** Sima Yu , initially the Prince of Langye , later the Prince of Kuaiji , later Emperor Jianwen of Jin
** Princess Xunyang
** Princess Nankang