The War of the Eight Princes, Rebellion of the Eight Kings, or Rebellion of the Eight Princes (simplified Chinese: 八王之乱; traditional Chinese: 八王之亂; pinyin: bā wáng zhī luàn; Wade–Giles: pa wang chih luan) was a series of coups and civil wars among kings/princes (Chinese: wáng 王) of the Chinese Western Jin dynasty from 291 to 306 AD. The period spanned the reign of Emperor Hui of Jin, whose powerful relatives fiercely contended with one another over his regency and succession in light of his developmental disability. The name of the conflict is derived from the biographies of the eight princes collected in Chapter 59 of the Book of Jin.
The "War of the Eight Princes" is somewhat of a misnomer: rather than one continuous conflict, the War of the Eight Princes saw intervals of peace interposed with short and intense periods of internecine conflict. At no point in the whole conflict were all of the eight princes on one side of the fighting (as opposed to, for example, the Rebellion of the Seven States). The initial conflicts prior to the coalition against Sima Lun in 301 were also not wars, but rather a series of political intrigues and coups d'état. The literal Chinese translation, Disorder of the Eight Kings, may be more appropriate in this regard.
While initial conflicts were relatively minor and confined to the imperial capital of Luoyang and its surroundings, the scope of the war expanded with each new prince who entered the struggle. The civil wars opened the empire to rebellions, most notably by tribal subjects that had resettled into the Central Plains. At its conclusion, the war devastated the Jin heartlands in northern China, and ushered in the Sixteen Kingdoms era in northern China, causing more than a century of warfare between the numerous short-lived dynasties in the north and the Eastern Jin dynasty in the south.
The Eight Princes
The "Eight Princes" is a Tang-era retrospective grouping from the joint biography of eight Sima family royals who held control over the Jin imperial court during the reign of Emperor Hui of Jin. Their biographies jointly appear in Chapter 59 of the Book of Jin (compiled 648 AD). The following table lists them in rough chronological order by the date each first held effective power at the Luoyang court. Generational labels follow descent from Sima Yi (司馬懿, 179–251), the dynasty's posthumously-honoured founder.
Other people of note included Emperor Hui of Jin, Emperor Hui's first regent Yang Jun, Empress Dowager Yang, Empress Jia Nanfeng, and the senior minister Wei Guan. It is also important to note that the fiefdom titles of the princes do not reflect their base of operation. Although Sima Ying was the Prince of Chengdu, he mostly operated in Ye and was never near his fief, while Sima Yong, the Prince of Hejian, mainly stayed around Chang'an. Only Sima Yue made use of his fief in Donghai as a base during the course of the conflict. The rest of the princes were in Luoyang at their respective height of power.
The conflict can be divided into two parts. The initial period (290–291) mainly concerns the power struggle between the Yang and Jia clans as they fought for control for Emperor Hui in the wake of his ascension. Sima Liang and Sima Wei were the only two of the Eight Princes involved, and fighting was only limited to coups in the capital, Luoyang. The later period (300–306) began following the fall of the Jia clan, who held power over the imperial court behind Emperor Hui for a decade before they were deposed by Sima Lun in 300. This period, particularly after Sima Lun's usurpation in February 301, escalated into a series of civil wars in northern China as Emperor Hui changed hands several times to the remaining six princes.
Background
In early 249, Sima Yi, an official, general, and regent of the state of Cao Wei during the Three Kingdoms period, effectively seized control of Wei after instigating a successful coup against his co-regent, Cao Shuang. Sima Yi and two of his sons, Sima Shi and Sima Zhao, came to serve as the de facto rulers of Wei in succession, while the Wei emperors were reduced to puppet rulers. In February 266, Sima Zhao's eldest son, Sima Yan, also known as Emperor Wu of Jin, forced the Wei emperor Cao Huan to abdicate the throne and established the Jin dynasty.
The Sima clan sought to learn from the mistakes that led to the Cao Wei's downfall. The Wei regime had previously discouraged their princes from holding government and military offices, instead sending them away to live in their fiefs. Sima Yi, with the backing of the powerful gentry clans, was thus able to take control over the Wei government with minimal resistance. Identifying this issue, Sima Yan bolstered his family power by enfeoffing his uncles, cousins, and sons with their own private armies. As time passed, these princes and dukes were given administrative powers over their lands and were granted the power to levy taxes and employ central officials. Many were also entrusted with important military responsibilities and given the right to command troops outside of their fiefdoms. These members were assigned to guard key cities such as Chang'an, Ye and Xuchang, as well as the Jin capital, Luoyang.
Additionally, Emperor Wu's reign was troubled by a succession crisis as he and many other became aware that his heir Sima Zhong was developmentally disabled. A faction of ministers in court wanted Wu's younger brother, the abled Sima You, to replace him as the Crown Prince, but Wu was adamant in upholding the traditional succession law that the eldest living son should succeed, just as his father, Sima Zhao had done for him. Zhong was strongly backed by both the influential Yang and Jia clans, being the son of Wu's first empress, Yang Yan and husband of Jia Nanfeng. Another factor for choosing Zhong was that Wu saw great potential in his grandson, Sima Yu, should he succeed Zhong in the future. In the end, Sima You's exile and untimely death in 283 effectively secured Sima Zhong's inheritance to the throne.
By empowering the princes, Emperor Wu intended for them to act as a safeguard for his successors should the gentry clans overstep their power, especially considering Sima Zhong's disability. He had hoped that his family members, by virtue of their familial ties, would cooperate with each other to protect the interests of their dynasty. However, after Sima Zhong took the throne and became a mere figurehead, the princes later proved themselves self-serving and willing to undermine one another for real control over the empire.
The War of the Eight Princes coincided with the upheaval of the so-called "Five Barbarians"; non-Chinese groups that had been resettling into the Chinese interior as far back as the Eastern Han dynasty. Through their civil wars and mismanagement of the empire, the Jin lost support from both the Chinese peasantry and the non-Chinese tribes, pushing them to join rebel groups in different parts of China. In 304, refugees from the Guanzhong led by the Ba Di founded the Cheng-Han dynasty in Sichuan, while the Five Divisions, descendants of the Southern Xiongnu, founded the Han-Zhao dynasty in Shanxi, thus beginning the Sixteen Kingdoms period. The princes also empowered the Xianbei tribes by employing them as auxiliaries in the final years of the conflict. South in the Yangtze region also saw the major rebellions of Zhang Chang and Chen Min, but these were ultimately suppressed.
Prelude: Yang Jun (290-291)
Ascension of Emperor Hui
In late 289, Emperor Wu developed a deadly illness and considered appointing his father-in-law, Yang Jun, and his uncle, the Prince of Ru'nan, Sima Liang, as Sima Zhong's regent. While the emperor's health declined, Yang Jun had plans to monopolize his control over Zhong as consort kin. He first sent Sima Liang away to Xuchang through an edict and then launched a smear campaign against his court rival, Wei Guan, and forced him into retirement. Yang Jun also hid the emperor's final decree appointing him and Sima Liang as co-regents while his daughter, the empress Yang Zhi, issued another edict making her father the sole regent. Emperor Wu was aware of Yang Jun's manipulations, but was too ill to stop him.
On 16 May 290, Emperor Wu died, and Sima Zhong, posthumously known as Emperor Hui of Jin, ascended the throne. Yang Jun was instated as his regent while Yang Zhi was promoted to Empress Dowager. However, Yang Jun was not well received by his ministers due to his blatant attempts at consolidating power and refusal to accept advice. He also tried to assassinate Sima Liang without success and rejected suggestions to cooperate with him. Meanwhile, the new empress, Jia Nanfeng, was unhappy with the little control she has over state affairs due to Yang Jun and the Empress Dowager.
Fall of the Yang clan
Empress Jia enlisted the help of Sima Liang and the Prince of Chu, Sima Wei to overthrow Yang Jun. Liang was reluctant to help her, but Wei, who was stationed with military command in Jing province at the time, agreed and left for the capital, Luoyang with his troops. On the night of 23 April 291, Empress Jia and her allies sent out an imperial edict calling for the deposal of Yang Jun and occupied the gates leading to his residence. Yang Jun was caught by surprise and struggled to plan his next move. Meanwhile, Empress Dowager Yang Zhi tried to entice the soldiers to turn on Empress Jia, but failed and implicated herself in the process.
Soon, the soldiers advanced and set fire to the residence. Yang Jun's soldiers were routed, and he was killed while trying to escape. His families, supporters were all rounded up and executed as the extermination of all third degree relatives. Yang Zhi was spared but confined inside the palace, where she remained until her death in 292.
Prince of Ru'nan, Sima Liang (291)
On 4 May 291, Sima Liang and Wei Guan were installed as the new regents of Emperor Hui. Now that he was in power, Liang asserted his authority by freely handing out new appointments and titles to around 1,081 people to garner support. At the same time, Empress Jia began placing her relatives and allies into positions of power.
Sima Liang and Wei Guan were wary of Sima Wei. Despite his role in the Yang clan's defeat, Sima Wei was notorious for his violent temperament. They attempted to strip him of his military power and send him back to his fief, but Wei retaliated by conspiring with Empress Jia to depose them, claiming to her that the two were planning to overthrow her. Soon, Empress Jia produced an edict from the emperor calling for the removal of Liang and Wei Guan. However, Wei was unsatisfied with the content of the original edict, as he was not included among the princes who had to raise their troops. Without the empress's knowledge, Wei forged an edict which made him Commander over all military forces and granted himself full control over the operation. On 26 July 291, he sent his subordinates and soldiers to arrest Liang and Wei Guan in Luoyang. Both men gave no resistance and were put to death.
Prince of Chu, Sima Wei (291)
Sima Wei was a half-brother of Emperor Hui. With the forged edict in hand, he had essentially placed himself in total command over the empire's military. Immediately after executing Sima Liang and Wei Guan, he was advised to utilize his military authority to execute Empress Jia's powerful relatives, Jia Mi and Guo Zhang. However, Wei was hesitant in accepting this plan. In Empress Jia's camp, the minister, Zhang Hua urged her to punish Wei for killing the emperor's regents. Just one day after Liang's death, Empress Jia deployed her troops against Wei and spread doubt regarding the edict's authenticity among his soldiers. Deserted by his followers, Wei was captured and executed. His full-brother Sima Ai the Prince of Changsha, who provided support, was demoted to the lesser title of Prince of Changshan as punishment.
Interlude: Empress Jia (291–300)
Power behind the throne
For the next nine years, Empress Jia ruled Jin in the emperor's name while entrusting power to her closest family members, most notably Jia Mi, and Guo Zhang. Despite the efforts of ministers like Zhang Hua and Pei Wei to uphold the government's functionality, the imperial court under the Jia clan was beset with widespread corruption and bribery. Rumors began to spread of Empress Jia's personal debauchery and tyrannical behavior, laying the seeds of discontent that would surface by the end of the decade.
Empress Jia also carried out a series of transfers that would influence the next stage of the War of the Eight Princes. In 296, a major tribal rebellion led by Qi Wannian broke out in Qin and Yong provinces under the watch of the Prince of Zhao and Emperor Hui's great-uncle, Sima Lun. Due to his failure to quell the uprising, Lun was recalled back to Luoyang. In 299, the Prince of Chengdu and half-brother of Emperor Hui, Sima Ying was assigned away to Ye following a heated argument he had with Jia Mi over the latter's treatment of the Crown Prince, Sima Yu. At the same time, the Prince of Hejian, Sima Yong, was transferred from Ye to the Guanzhong region in the west. Yong was a second cousin of Emperor Wu, but a grandson of the distinguished Sima Fu, and through the endorsement of the gentry clans he was entrusted to guard an important region.
The rebellion in Qin and Yong coincided with famines and plagues, and although it was ultimately put down in 299, it sparked an influx of refugees fleeing south to Yi province. It also allowed a Di leader, Yang Maosou to set up the state of Chouchi south of Tianshui in 296.