Emperor Hui of Jin (; 259 – 8 January 307), personal name Sima Zhong (), courtesy name Zhengdu (), was the second emperor of the Western Jin dynasty. Emperor Hui was a developmentally disabled ruler, and throughout his reign, there was constant internecine fighting between regents, imperial princes (his great-uncle, half-brothers and distant cousins), and his wife Empress Jia Nanfeng for the right to control him (and therefore the imperial administration), causing great suffering for the people and greatly undermining the stability of the Western Jin dynasty, eventually leading to rebellions of the Five Barbarians that led to Jin's loss of northern and central China and the establishment of the competing Sixteen Kingdoms. He was briefly deposed by his granduncle Sima Lun, who usurped the throne himself, in February 301, but later that year was restored to the throne and continued to be the emperor until January 307, when he was poisoned, likely by his last regent Sima Yue.
Life prior to ascension Sima Zhong was born to Sima Yan and his wife Yang Yan in 259 AD, while Sima Yan was still the assistant to his father, the Cao Wei regent Sima Zhao. He was their second son, but after the early death of his older brother Sima Gui (), he became the oldest surviving son. It is not known when his developmental disabilities became apparent. In any case, after Sima Zhao died in September 265, and Sima Yan subsequently forced the Cao Wei emperor Cao Huan to abdicate to him in February 266, he made the nine-year-old (by East Asian reckoning) Prince Zhong crown prince in 267 AD.
As Crown Prince Zhong grew in age, his developmental disabilities became clear to his parents and the imperial officials alike. He learned how to write and speak, but appeared to be unable to make logical decisions on his own at all. Once, when he heard frogs croaking, he asked, in all seriousness, "Do they croak because they want to, or because the government ordered them to?" Several times, officials reminded Emperor Wu of this, but Emperor Wu, not realizing the extent of Crown Prince Zhong's disability, resisted the implicit calls for him to be replaced. Indeed, because Emperor Wu was concerned that many officials were impressed with his talented younger brother, Sima You the Prince of Qi and might want Prince You to replace him instead, he eventually had Prince You sent to his principality, and Prince You died in anger in April 283.
On 2 April 272, at age 13, Crown Prince Zhong married Jia Chong's daughter Jia Nanfeng, who at 14 was two years older. Possibly biased histories describe Crown Princess Jia as violent and jealous, but she had her methods of controlling Crown Prince Zhong so that he both loved and feared her. They had four daughters during their marriage, but his only son, Sima Yu, was born to Consort Xie Jiu. Consort Xie was originally a concubine of Emperor Wu, but had been given to Crown Prince Zhong prior to his marriage to Crown Princess Jia, so that Consort Xie could teach him how to have sexual relations. Sima Yu was much favored by his grandfather Emperor Wu. Emperor Wu considered Prince Yu intelligent and very much like his own grandfather Sima Yi, and this played into his decision not to replace Crown Prince Zhong. However, other than Crown Princess Jia and Lady Xie, no other consort would bear Crown Prince Zhong a child, as Crown Princess Jia ordered each pregnant concubine murdered in fits of jealousy.
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 in May, and Crown Prince Zhong ascended the throne as Emperor Hui. Crown Princess Jia became empress, and Prince Yu became crown prince.
Reign During his 16-year reign, Emperor Hui would come under the control of a number of regents and de facto princes, never being able to assert authority on his own. The rough succession order of the regents and de facto princes were: Yang Jun: May 290 – 23 April 291 Sima Liang/Wei Guan: 4 May to July 291 Empress Jia Nanfeng: July 291 – May 300 Sima Lun: May 300 – May 301 Sima Jiong: June 301 – January 303 Sima Ai: January 303 – March 304 Sima Ying: April 304 - February 305 Sima Yong: February 305 – June 306 Sima Yue: June 306 – January 307
Regency of Yang Jun Yang Jun quickly showed himself to be autocratic and incompetent, drawing the ire of many other nobles and officials. He tried to appease them by making many bestowments of titles and honors among them, but this only brought further contempt for his actions. He knew Emperor Hui's empress Jia Nanfeng to be strong-willed and treacherous, so he tried to put people loyal to him in charge of all the defense forces of the capital Luoyang, and also ordered that all edicts not only be signed by the emperor but also by Empress Dowager Yang before they could be promulgated.
Empress Jia, however, wanted to be involved in the government, and was angry that she was constantly rebuffed by Empress Dowager Yang and Yang Jun. She therefore conspired with the eunuch Dong Meng () and the generals Meng Guan () and Li Zhao () against the Yangs. She tried to include Sima Liang in the conspiracy, but Sima Liang declined; instead, she persuaded Emperor Hui's brother, Sima Wei the Prince of Chu, to join her plan. In April 291, after Sima Wei returned to Luoyang from his defense post with his troops, a coup went into progress.
Empress Jia, who had her husband easily under her control, had him issue an edict declaring that Yang Jun had committed crimes and should be removed from his posts. It also ordered Sima Wei and Sima Yao () the Duke of Dong'an to attack Yang's forces and defend against counterattacks. Quickly, it became clear that Yang was in trouble. Empress Dowager Yang, trapped in the palace herself, wrote an edict ordering assistance for Yang Jun and put it on arrows, shooting it out of the palace. Empress Jia then made the bold declaration that Empress Dowager Yang was committing treason. Yang Jun was quickly defeated, and his clan was massacred. Empress Dowager Yang was deposed and imprisoned. Sima Liang was recalled to serve as regent, along with the senior official Wei Guan.
Regency of Sima Liang and Wei Guan To appease those who might have been angry and had overthrown Yang Jun, Sima Liang also widely promoted those who participated in the plot, and more than a thousand men were created marquesses. He and Wei, however, did try to get the government on track, but Empress Jia continued to interfere with governmental matters. They also became concerned about the violent temper of Sima Wei and therefore tried to strip him of his military command, but Sima Wei persuaded Empress Jia to let him keep his military command. Sima Wei's assistants Qi Sheng () and Gongsun Hong () thereafter falsely told Empress Jia that Sima Liang and Wei planned to depose the emperor. Empress Jia, who had already resented Wei for having suggested that the heir selection be changed during Emperor Wu's reign, desired more direct control over the government, and therefore resolved to initiate a second coup d'état.
In summer 291, Empress Jia had Emperor Hui personally write an edict to Sima Wei, ordering him to have Sima Liang and Wei removed from their offices. His forces thereby surrounded Sima Liang and Wei's mansions, and while both men's subordinates recommended resistance, they each declined and were easily captured. Contrary to the edict's terms, both were killed—Sima Liang with his heir Sima Ju () and Wei with nine of his sons and grandsons. Qi then suggested to Sima Wei to take the opportunity to massacre Empress Jia's relatives and take over the government himself, but Sima Wei hesitated— at the same time, Empress Jia came to the realization that if the murders of Sima Liang and Wei could be traced to her instigation, that would bring a political firestorm' also that Sima Wei could not be easily controlled. She therefore publicly declared that Sima Wei had falsely issued the edict. Sima Wei's troops abandoned him, and he was captured and executed. Sima Liang and Wei were posthumously honored. From this point on, Empress Jia became the undisputed power behind the throne for several years.
Empress Jia behind the throne Empress Jia now issued imperial edicts for whatever she wanted through her husband Emperor Hui and in his name, she received and responded to the memorials and petitions of the officials; she also to control the government in close association with several advisors that she trusted—the capable official Zhang Hua, her cousins Pei Wei and Jia Mo (), and her nephew Jia Mi (originally named Han Mi but posthumously adopted into the line of Jia Chong's son Jia Limin ()). She also closely associated with her distant cousin-once-removed Guo Zhang (), her sister Jia Wu (), and Emperor Wu's concubine Zhao Can (). She lacked self-control, and was violent and capricious in her ways, but Zhang, Pei, and Jia Mo were honest men who generally kept the government in order. However, as she grew increasingly unbridled in her behavior (including committing adultery with many men and later murdering them to silence them), Zhang, Pei, and Jia Mo considered deposing her and replacing her with Crown Prince Yu's mother Consort Xie, but they hesitated and never took actual action. After Jia Mo died in 299, it became even harder to control her actions.
In 296, the Di and Qiang of Qin (, modern eastern Gansu) and Yong (, modern central and northern Shaanxi) started a major rebellion against Jin dynasty, and they supported the Di chieftain Qi Wannian to be emperor. In 297, the Jin general Zhou Chu (), without support from the central government, was easily defeated by Qi. A large group of refugees, most of Di ancestry, stricken by the famine that resulted from the warfare, fled south into Yi Province (modern Sichuan and Chongqing), led by Li Te. (Several years later, they would eventually be forced into rebellion and peel away from Jin rule.) In February or March 299, Meng Guan was able to defeat Qi, but Qi foreshadowed much more serious non-Han rebellions of the future. Soon after the rebellion was put down, the mid-level official Jiang Tong (江統) would petition Empress Jia to have the non-Han tribes removed from the empire proper and relocated to regions outside the empire, but Empress Jia did not accept his suggestions.Zizhi Tongjian, vol.83. In Tongjian, Jiang Tong's petition was the next event recorded after Qi Wannian's capture in the 1st month of that year.