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 civil wars among kings/princes (Chinese: wáng 王) of the Chinese Jin dynasty from AD 291 to 306. The key point of contention in these conflicts was the regency over the developmentally disabled Emperor Hui of Jin. The term stems from biographies of eight princes collected in chapter 59 of the Book of Jin (Jinshu).
Technically, the term "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 literal Chinese translation, Disorder of the Eight Princes, 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 that entered the struggle. At its conclusion, the war devastated the Jin heartlands in northern China, and was a major cause of the Wu Hu ravaging that ended the Western Jin.
While many princes participated in the conflict, the eight major players in this conflict were:
Sima Yi, from whom the Sima clan began its rise to power, had managed to take control of Cao Wei due to the lack of a Cao nobility that had the means to contest the authority of the Sima Yi-controlled central government.
In 265, Sima Yan forced Cao Huan to abdicate and established the Jin dynasty. Mindful of historical precedent, Sima Yan sought to bolster the power of the Sima clan by enfeoffing his uncles, cousins and sons. Big enfeoffments were entitled to an army of five thousand; intermediate enfeoffments an army of three thousand, and small enfeoffments an army of one thousand five hundred. As time passed, these princes and dukes were also given administrative powers over their lands, and also were granted the power to levy taxes and employ central officials.
Following the death of Sima Yan, i.e. Emperor Wu, in 290, a complex power struggle began amongst the Sima clan. The new emperor, Emperor Hui, was developmentally disabled. Initially, the emperor's stepmother, Empress Dowager Yang, exerted the most power at court, and empowered her family, the Yang consort clan, with her father Yang Jun given the most power.
The emperor's wife, Empress Jia Nanfeng, who was not happy with being excluded from this state of affairs, enlisted the help of Sima Wei and Sima Liang. Sima Wei's troops entered Luoyang unilaterally and unopposed by the central government. In 291, Empress Jia issued an edict accusing Yang Jun of treason. Sima Wei's troops killed Yang Jun, the empress dowager was starved to death under house arrest, and 3000 members of the Yang clan were executed. Thus began the intervention of the princes in the affairs of the central government.
Power was now in the hands of Sima Liang, the emperor's grand-uncle, and Wei Guan. However, Empress Jia remained unsatisfied with her lot. She thus plotted with Sima Wei, who was in control of a battalion of the imperial guards, and was himself under pressure from Sima Liang to return to his fief of Jing Province. Again issuing an imperial edict accusing Sima Liang of treason, the empress and Sima Wei killed Sima Liang (Sima Wei's grand-uncle) and Wei Guan.
Immediately following the killing of Sima Liang, Sima Wei was advised to expand his power at the expense of Empress Jia. Sima Wei hesitated. Two days after Sima Liang's death, Empress Jia spread a rumor around Sima Wei's camp accusing him of forging the imperial edict that killed Sima Liang. Deserted by his followers, Sima Wei (Empress Jia's brother-in-law) was captured and executed.
Empress Jia thus became the sole power at court, with members of her consort clan and trusted subordinates being promoted to high positions. The political situation from 291 to 299 was relatively stable, but 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.
The heir to the Jin dynasty, Sima Yu, was the son of Emperor Hui and Consort Xie, and as such posed a political threat to Empress Jia. In 299, Empress Jia convinced a drunk Sima Yu to copy a text that said, amongst other things, that Emperor Hui should abdicate in favor of Sima Yu. Empress Jia then presented the copied text to Emperor Hui, who after discussion decided to execute his son. Empress Jia desired the punishment to be carried out immediately; but Emperor Hui decided instead to merely depose Sima Yu and keep him under house arrest for the time being.
Sima Lun, at this time, was the tutor to the prince and considered a member of Empress Jia's inner circle. Unbeknownst to Empress Jia, however, Sima Lun was actually plotting to overthrow Empress Jia. However, his advisor Sun Xiu argued that, because of Sima Lun's reputed loyalty to the Empress, Sima Lun's actions would only lead to the accession of Sima Yu, who would then exact revenge on Sima Lun himself. Sima Lun thus decided to have Empress Jia kill Sima Yu first before acting, and thus encouraged Empress Jia to kill Sima Yu (Sima Lun's great grand-nephew).
All went according to plan and Empress Jia murdered Sima Yu. Then Sima Lun, producing an edict allegedly from Emperor Hui, arrested Empress Jia and put her under house arrest, and later forced to commit suicide in 300. Sima Lun, again by way of forged imperial edict, first appointed himself as Grand Vizier and, in 301, crowned himself emperor, putting Emperor Hui under house arrest.
Sima Lun's usurpation of the throne was hotly contested by the other princes. Three major princes allied themselves to oppose him: in Xuchang, the Prince of Qi Sima Jiong; in Chang'an, the Prince of Hejian Sima Yong, and in Chengdu the Prince of Chengdu Sima Ying.
After a campaign lasting 60 days and with tens of thousands dead on both sides, Sima Lun's forces were defeated and he was himself put under house arrest, being forced to commit suicide not long after. The supporters of Sima Lun were also hunted down and exterminated.
Sima Jiong reinstated Emperor Hui as the rightful ruler of Jin, and appointed himself Grand Marshal. Simas Yong and Ying were also given high positions. Sima Jiong, however, abused his position, acting as if he was himself emperor.
In 302, Sima Yong, claiming that the Emperor had secretly ordered him to fight Sima Jiong (his second cousin once removed), rose in rebellion and marched towards Luoyang. Sima Yong, intending to take Luoyang with as little casualties as possible, hatched a ruse against Sima Jiong.
Sima Yong claimed that the Prince of Changsha, Sima Ai, was actually his contact in Luoyang. Upon hearing the news, Sima Jiong sent troops to kill Sima Ai; however, Sima Ai escaped and fled to the imperial palace for protection. There, using both imperial guards and his own personal forces, Sima Ai fought Sima Jiong (his second cousin) within Luoyang itself for three days. Sima Jiong lost and was killed, and his supporters exterminated.
Sima Yong was not happy about this state of affairs. He had expected Sima Ai to lose, thus allowing Sima Yong to enter Luoyang, kill Sima Jiong, replace Emperor Hui with the Prince of Chengdu, Sima Ying (Emperor Hui's and Ai's brother and Sima Yong's second cousin once removed), and appoint himself as Prime Minister. The stage was set for another conflict.
Unhappy with Sima Ai's influence at court, Sima Yong attempted to assassinate Sima Ai, but his efforts were in vain. So in 303, he allied himself with the Prince of Chengdu, Sima Ying, raised an army of 270,000 men and moved against Luoyang. In response, Emperor Hui appointed Sima Ai as Grand Commander and sent him to combat the rebellious princes. Sima Ai's armies killed tens of thousands of enemy forces, but were forced to withdraw back to Luoyang due to logistical issues.
Seeing this, Minister of Works Sima Yue kidnapped and put Sima Ai (his second cousin once removed) under house arrest. Later, fearing the consequences should Sima Ai escape, Sima Yue sent Sima Ai to Sima Yong (Sima Yue's second cousin), who burnt Sima Ai alive.
The armies of Simas Yong and Ying entered Luoyang in triumph. Simas Yue and Yong were appointed to high posts in government, while Sima Ying was enfeoffed with an additional 20 commanderies, and designated the imperial heir.
From his base in Ye, the Prince of Chengdu Sima Ying lived a lavish lifestyle and his ambition to become Emperor soon was apparent. Sima Yue and Emperor Hui therefore led an army of 100,000 against Sima Ying (Sima Yue's second cousin once removed).
However, the imperial forces were defeated at the Battle of Dangyin. Emperor Hui was captured by Sima Ying, who relocated him to Ye. Luoyang fell to the troops of Sima Yong, who decided to assist Sima Ying. Sima Yue fled back to his base in Donghai (southeastern Shandong). Power was thus further consolidated under Sima Ying.
Sima Ying, under the pretext of familial love, urged Sima Yue to return to the imperial court, but Sima Yue rejected his offers.
Sima Yue's brother, the Duke of Dongying Sima Teng (Traditional Chinese: 東瀛公 司馬騰) rose up against Sima Ying in You Province. Enlisting the help of barbarians such as Wuhuan, he defeated Sima Ying's forces.
Sima Ying fled with Emperor Hui to Luoyang, which was then occupied by Sima Yong. Sima Yong took possession of Emperor Hui (his second cousin once removed), moved him to Chang'an, and stripped Sima Ying of his position as heir. Sima Yong, now the power behind the throne, offered to share the regency with Sima Yue, an offer that was rebuffed.
Sima Yong intended to send Sima Ying with a token force to garrison Ye (thereby removing him from imperial politics), but these plans were disrupted when Sima Yue again rebelled against the central government.
Sima Yue rebelled against Sima Yong in 305, enlisting the help of his brothers in the North China Plain. Sima Yong attempted to deprive Sima Yue of legitimacy by officially stripping him of all titles, but in response Sima Yue claimed that he was "rescuing the Emperor from his kidnappers and returning him to Luoyang".
The forces of Sima Yong and Sima Yue met in central Henan. Although Sima Yong was initially victorious, timely reinforcements from the Prince of Fanyang, Sima Chu (Sima Yue's cousin), mostly consisting of barbarian troops, helped turn the tide. By 306 Sima Yue had conquered Chang'an, which his forces plundered. Sima Yong fled to Mount Taibai, while Sima Ying fled towards Ye. Sima Yue became the latest prince to dominate the imperial court, which he moved back to Luoyang.
While fleeing, Sima Ying was captured and put under house arrest by Sima Chu (to whom Sima Ying was a second cousin once removed). A month later, however, Sima Chu died under mysterious circumstances. Owing to the fact that Sima Ying had deep roots in Ye, the subordinates of Sima Chu murdered Sima Ying and his family, using a false edict as justification.
Meanwhile, Sima Yong had taken up arms again and captured Chang'an, but was unable to advance much further than the Guanzhong region. Both sides therefore settled down into a stalemate.
Emperor Hui died under mysterious circumstances in 307 (possibly poisoned by Sima Yue). The new Emperor, Emperor Huai, was a brother of the former ruler. As part of the accession rituals, Emperor Huai issued an edict ordering Sima Yong to come to court as Minister over the Masses. As Sima Yong was on his way, however, forces loyal to the Prince of Nanyang Sima Mo killed him and his family.
While other princes still existed, the position of Sima Yue, the Prince of Donghai, was uncontestable. However, his victory was short-lived. Already by 308 the barbarian state of Han Zhao was able to conquer Xuchang in central Henan; by 309 Sima Yue was already fighting a civil war against another minister, Gou Xi; and by 311 Sima Yue would die amidst an empire-wide campaign, led by Emperor Huai, to exterminate him.
In an eerily analogous manner to the fall of the Roman Empire on the other side of Eurasia, barbarian tribes, taking advantage of the turmoil within the Western Jin and aided by the liberal use of mercenaries by the various Princes, began establishing self-governing kingdoms within China proper. By 311 the largest barbarian state, Han Zhao, would conquer the Jin capital at Luoyang; and by 316, would capture the co-capital of Chang'an as well, thus ending the Western Jin and ushering in a nearly three-centuries-long division of China.
The War of the Eight Princes severely damaged the traditional Chinese economic heartlands in the lower Yellow River. Coupled up with the subsequent barbarian invasions, this led to large-scale population and economic shifts from the North China Plain to the lower Yangtze and Sichuan Basin. It was also a major contributing factor in the Sinicization of southern China. For example, the modern inhabitants of Fujian are largely descendants of Jin refugees from Northern China; this is reflected in the similarities that Min languages have with Old Chinese.