War of the Eight Princes

In late 289, Emperor Wu developed a deadly illness. His heir, Sima Zhong was developmentally disabled, but was his eldest surviving son. Zhong was also the grandson of the influential minister, Yang Jun through his daughter, Empress Yang Zhi. As the emperor's health declined, Yang Jun sought to monopolize control over his successor as consort kin, sending away the emperor's uncle, the Prince of Ru'nan, Sima Liang to Xuchang and forcing his court rival, Wei Guan, into retirement. Yang Jun also hid the emperor's final decree appointing him and Sima Liang as co-regents while Yang Zhi issued another edict making her father the sole regent.

On 16 May 290, Emperor Wu died, and Sima Zhong, later 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 apparent attempts at consolidating power and refusal to take advice. He also tried to assassinate Sima Liang without success and was adamant against cooperating with him. Meanwhile, Emperor Hui's wife, Empress Jia Nanfeng, was unhappy with the little control she has over state affairs due to Yang Jun and the Empress Dowager.

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 agreed and left his fief 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 was unable to decide on his next move. Empress Dowager Yang Zhi tried to get 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, while he was killed while trying to escape. His brothers, supporters and their families were all rounded up and executed to the third degree. Yang Zhi was spared but placed under house arrest, where she remained until her death in 292.

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.[5][6]

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, Sima Lun. Due to his failure to quell the uprising, Lun was recalled back to Luoyang. Later on, the Prince of Chengdu, Sima Ying was assigned away to Ye following a heated argument he had with Jia Mi, while the Prince of Hejian, Sima Yong, was garrisoned in Guanzhong.

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.[7]

Empress Jia deemed the Crown Prince, Sima Yu as a threat to her power should he ascend the throne, since he was not her biological son. In 299, she orchestrated his arrest by convincing him while drunk to copy a text that said, amongst other things, that Emperor Hui should abdicate in favor of him. Empress Jia then presented the copied text to Emperor Hui, who then decided to place him under house arrest.[8]

Sima Lun was tutor to the prince at the time and had climbed his way into Empress Jia's inner circle during his time in Luoyang. He also commanded some troops in the capital as general of the Right Army and was known to be "avaricious and false" as well as "simple and stupid," heeding only the advice of Sun Xiu. Yu's arrest sparked outrage among many officials, and a few of them approached Lun for his military strength to overthrow Empress Jia.

Lun had long wished to betray the empress, but Sun Xiu convinced him to wait until Yu was out of the way, arguing that because of Lun's reputed loyalty to the empress, Lun's actions would only lead to the accession of Yu, who would then exact revenge on Lun himself. With Lun's encouragement, the empress had Yu assassinated. Lun then produced an edict allegedly from Emperor Hui calling for her removal. On 7 May 300, he arrested Empress Jia and put her under house arrest, and later forced her to commit suicide by drinking gold powered wine.[9] He also executed many of her partisans, including Jia Mi, Zhang Hua and Pei Wei.

Sima Lun assumed regency over Emperor Hui, but delegated most of his power over to Sun Xiu. Lun and Sun Xiu plotted to take the throne by following the precedent of the Jin dynasty's foundation. They awarded their family members and allies with high-ranking positions and noble titles, while also posthumously honoring Sima Yu and recruiting famed individuals into their administration to win the people's support. Yang Xianrong, a distant relative of Sun Xiu, was installed as the new empress of Emperor Hui.

In autumn 300, after Lun attempted to take his military authority away, the Prince of Huainan, Sima Yun rebelled against Lun with only 700 men in Luoyang. Lun was nearly killed in the fighting, but one of his supporters pretended to defect to Yun and killed him, ending his rebellion.[9] The rebellion provided Lun and Sun Xiu with pretext to purge their court rivals and opposition. Meanwhile, the Prince of Qi, Sima Jiong, who played a vital part in Empress Jia's arrest, was unhappy with his positions he received in Lun's administration. Sensing his discontent, Lun had Jiong assigned away to Xuchang.

After Yun's rebellion, Lun was granted the Nine Bestowments. The following year, he claimed in a report that the spirit of his father, Sima Yi, had ordered him to move into the Western Palace (西宮), the residence of Emperor Hui. He then forged an edict stating the self-abdication of Emperor Hui and usurped the throne on 3 February 301.

During Lun's regency, the Inspector of Yi Province, Zhao Xin, a relative of Empress Jia, rebelled against following his coup. In early 301, his rebellion was quelled after his subordinate, the Ba-Di refugee leader, Li Te, betrayed and ousted him from Chengdu.

Not long after his usurpation, Sima Jiong sent out a proclamation to campaign against Sima Lun. The most important figure to accept his call was Sima Ying. Ying was described as beautiful but dull in the mind and did not read books, but he heeded his advisor Lu Zhi's advice to rally the people to his cause. Some 200,000 troops, including the forces of Prince of Changshan, Sima Ai, were thus assembled near his base in Ye. In Chang'an, Sima Yong initially dispatched troops to support Lun but later sided with the coalition after learning that they were larger in size.[10] Due to their strategic bases and command over vast armies, Jiong, Ying and Yong were collectively referred to as the "Three Princes" (三王) in records. Another notable participant of the coalition was the Duke of Xinye, Sima Xin.

Lun sent Zhang Hong (張泓) and Sun Fu (孫輔) with 24,000 men to secure the passes and 30,000 under Sun Hui (孫會) to confront Ying. Zhang Hong fought Jiong at Yangdi (陽翟, modern Yuzhou, Henan) and defeated him several times before Jiong retreated and made camp at Yingyin (潁陰; in present-day Xuchang, Henan). However, one night, a disturbance occurred in Sun Fu's camp, causing him to flee back to Luoyang and claim that Zhang Hong was defeated. Lun recalled a segment of his army to defend Luoyang, but when news of Zhang Hong's recent victories reached him, he sent them out again to attack Sima Ying. However, by this time Jiong had reversed his early defeats and repelled Zhang Hong back to his camp.

Sun Hui led the main army against Ying at Huangqiao (黃橋, in present-day Wen County, Henan), defeating the prince's vanguard and killing 10,000. Ying planned to retreat back to Zhaoge, but Lu Zhi advised him to carry out a surprise attack during the early morning. Sun Hui and his contemporaries were complacent by their recent victory and did not prepare any defense. Ying rallied his troops and returned with a counterattack, smashing Hui's forces north of the Yellow River.[11] Ying's army was the first to make a breakthrough as they crossed the Yellow River to march on Luoyang.

As the coalition forces approached, officials and generals in the capital began to turn on Lun and Sun Xiu despite their attempts to surpress reports of their losses. The defeat at Huangqiao left Sun Xiu's camp greatly alarmed as they struggled to devise a plan in response. On 30 May 301, the general of the Left Guard led troops into the palace and arrested Lun. Sun Xiu and many of Lun's supporters were also captured and executed. Lun spent the next few days denouncing his own conduct before he was forced to commit suicide.

Emperor Hui was reinstated and celebrated the occasion with a five-day non-stop drinking binge. Ying was the first to reach the capital on 1 June, followed by Yong on 7 June. Jiong was still fighting Zhang Hong's forces at Yangdi at the time, so Ying had to send his soldiers to assist him. After Zhang Hong and his peers surrendered, Jiong entered the capital with "several hundred thousand armored soldiers, before whom the capital trembled in awe" on 23 July.[11]

On 11 August 301, Sima Jiong received the Nine Bestowments and was made regent of Emperor Hui. Jiong had intention to share his regency with Sima Ying, but through the advice of Lu Zhi, Ying withdrew to Ye to care for his ailing mother and handed over all major responsibility to Jiong. At Ye, Ying carried numerous popular policies to win over the people. He arranged for grain to be transported to the famine-stricken region of Yangdi, which had been devastated by war. He then had over 8,000 coffins constructed for high-ceremony funerals of those who had fallen in battle and over 14,000 of Sima Lun's soldiers to be buried. These were all Lu Zhi's ideas.[12]

In mid-302, the last of Sima Yu's lineage died, throwing the line of succession into confusion. Sima Jiong designated the Emperor's nephew, Sima Tan, as crown prince. At the same time, Sima Yue, Prince of Donghai, was appointed to direct the Central Secretariat.[12] Throughout his regency, Jiong alienated many of his ministers due to his arrogant and extravagant personality. He rarely visited the emperor and attended court meetings, and despite multiple attempts to get him to change his ways, he was reluctant to follow through his supporters' advices.

The minister, Wang Bao, was concern about the various princes' military power, believing that they would one day use it against Jiong just as they did with his predecessors. In a letter to Jiong, Wang Bao urged him to send the princes back to their respective fiefs and to divide control over the state between him and Sima Ying. Jiong was initially convinced, but when the Prince of Changsha, Sima Ai, discovered the plan, he prompted Jiong to reject it and have Wang Bao executed.

Shortly after Lun's defeat in 301, the court issued an edict ordering refugees in Yi province to return north. However, many of them, including Li Te, refused to comply with the edict. In winter 301, the provincial inspector, Luo Shang declared war against Li Te.

Jiong wanted to appoint Li Han, one of Sima Yong's chief of staff, to be colonel of the Army of Readiness. Li Han was afraid to accept the appointment due to enmity between himself and Huangfu Shang, one of Jiong's advisers. Li Han fled back to Yong and conspired with him to rebel against Jiong. Yong was told to align himself with Sima Ying, offering him the role of Crown Prince due to his public support. He was also told to force Sima Ai, who was in Luoyang, into joining so that Jiong would execute him and provide justification to overthrow him.

In January 303, Yong rebelled while Ying, despite opposition from Lu Zhi, was tempted to join him. Yong sent Li Han and Zhang Fang to campaign against Jiong, and they sent a proclamation to ordering Ai to attack Jiong. Believing that Ai was involved, Jiong sent troops to kill him, who fled to the imperial palace for protection. There, using both imperial guards and his own personal forces, Ai defended the palace against Jiong within Luoyang for three days, bringing Emperor Hui along with him. On 27 January, Jiong's own officers betrayed him and he was captured and killed.[13]

Sima Ai seized control of the capital but deferred authority to his brother, Sima Ying.[13] The outcome of the conflict put a halt to Sima Yong and Ying's plans, which frustrated the two princes. Ying in particular was unhappy with his restricted control over the state as he shared power with Ai, and the relationship between the brothers deteriorated over time.

Ai's administration failed to deal with rebel movements in the empire. In the southwest, Li Te's rebellion raged on despite his death. Along the Changjiang, rebels consisting of refugees and draft evaders led by the Man leader, Zhang Chang took up arms.[13] When the court ordered Sima Yong to campaign against Zhang Chang, he refused to move his troops. Later, when the Prince of Xinye, Sima Xin, asked for permission to send his troops out, Ai rejected his request, believing that Xin was colluding with Ying, who he had good relations with, and plotting to rebel. Xin was killed in battle by the rebels, and Zhang Chang's rebellion spread throughout the southern provinces.

Ai also emloyed Huangfu Shang as an advisor, putting Li Han at unease. Shang had a brother, Huangfu Zhong, who was the Inspector of Qin province, which placed him in a position to threaten Sima Yong's rear in Guanzhong. Yong and Li Han conspired to have him arrested, but he saw through their plans and led his troops to attack Li Han. Ai tried to defuse the situation by recalling Li Han to Luoyang and ordering Zhong to disperse his troops, but Zhong refused. Finally, Yong secretly ordered Li Han to have Ai assassinated. Huangfu Shang discovered their plot and informed Ai, and so the prince had Li Han executed.[14]

After the failed assassination attempt, Yong prepared his troops for war. At the time, Sima Ying was setting out to quell Zhang Chang's rebellion, but hearing about the situation in Luoyang and Guanzhong, he took his troops to join Yong instead, once again ignoring Lu Zhi's advice. In fall 303, Yong sent an army of 70,000 under Zhang Fang to attack the capital. Ying also sent an army 200,000 strong under Lu Ji against the capital.

Uncharacteristically, Emperor Hui commanded his own troops to help Sima Ai defend Luoyang. On 21 September 303, Ai sent 10,000 men under Huangfu Shang to oppose Zhang Fang, but he was defeated in a surprise attack. Zhang Fang momentarily broke through the city walls and carried out a mass plundering before withdrawing. Meanwhile, Emperor Hui was constantly on the move and shifting his base before he defeated Ying's troops at Goushi (緱氏; in present-day Yanshi District, Henan) on 22 October. However, when Shi Chao threatened his position at Goushi, he returned to the palace a few days later.

On 2 November, Ai's forces defeated Ying's army again outside of Luoyang. The next day, Ai brought with him Emperor Hui andpersonally confronted Lu Ji's army at the city gates. Ai's officers had several thousand cavalry equipped with double-ended halberds charge Lu Ji's forces, heavily defeating them. Many of Lu Ji's officers were killed, and the dead on his side reportedly laid in piles and clogged the river. Lu Ji managed to escape but was arrested and executed on Ying's orders. Meng Jiu (孟玖) replaced him as head of military operations.[15]

Ai then moved west to face Zhang Fang. The emperor's presence caused panic within Zhang Fang's army, so he was badly defeated and lost 5,000 soldiers. Zhang Fang rejected his subordinates' advice to retreat and instead secretly constructed ramparts during the night. Ai thought that Zhang Fang had been dealt with, but after realizing that the ramparts had been completed, he attacked them unsuccessfully.[16]

Ai's officials attempted to negotiate peace with Ying, seeing that the two were brothers. However, when offered to split the empire between him and Ai, he rejected it. Ai personally wrote a letter to Ying to persuade him, but Ying would only accept it if Ai executed Huangfu Shang, which Ai refused to do.[16]

Zhang Fang severed the Qianjin Dam (千金堨), effectively cutting off Luoyang's water supply. In response, Ai convinced the Inspector of Yong province, Liu Chen, to defect from Yong's side and attack Chang'an. He also sent Huangfu Shang out with an edict from the emperor to get the generals attacking Huangfu Zhong to disband, thus allowing him to send reinforcements to Luoyang. However, along the way, Huangfu Shang was captured and killed.

Ai held out in Luoyang until March 304, and by this point, Zhang Fang had given up hope of taking Luoyang and was planning to withdraw. Despite this fact, the Minister of Works, Sima Yue feared that Ai would not succeed in the long run. On March 17, he and a group of officials kidnapped and put Ai under house arrest. The next day, they opened the gates and surrendered to the enemy forces. However seeing how few of the opposing army remained, the capital troops regretted surrendering and secretly plotted to free Ai. Fearing the consequences should Ai escape, Yue sent Ai to Zhang Fang, who put Ai to the torch.[17]

Although Ai was defeated, Yong was still threatened by Liu Chen, while Huangfu Zhong continued to resist in his city of Jicheng (冀城; in present-day Gangu County, Gansu). Yong recalled Zhang Fang to deal with Liu Chen, who had defeated a subordinate army on his way to Chang'an. On his way back, Zhang Fang seized over 10,000 slave women in Luoyang and cut them into mince meat to feed to his men. Liu Chen defeated Yong in succession, and 5,000 of his soldiers were able to break into Chang'an. However, he was slow to capitalize on his success, and the soldiers in Chang'an were eventually killed while Zhang Fang arrived just in time to defeat and capture him.[18]

After Sima Ai's death, Sima Ying appointed himself Prime Minister and promoted Sima Yue to President of State Secretariat. Despite his new position, Ying kept Emperor Hui at Luoyang, leaving behind an army of 50,000 under Shi Chao while he returned to his base in Ye. On April 304, he imprisoned the empress, Yang Xianrong, and depose his nephew, Sima Tan from the position of Crown Prince. On 1 May, Ying was installed as Crown Prince and his power was described as being equal to that of Cao Cao during the end of the Han dynasty. Sima Yong was also appointed the Grand Governor and Grand Commander. As Crown Prince, Ying was said to have become more brazen and extravagant in his actions and was inclined towards favoritism, which lost him some of the goodwill from his supporters.[18]

On 17 August 304, Sima Yue rebelled in Luoyang, restoring Yang Xianrong and Sima Tan to their positions as Shi Chao and the others fled for Ye. He amassed an army of over 100,000 at Anyang and marched on Ying's capital, bringing with him Emperor Hui. Along the way, Yue was errorneously informed that the soldiers in Ye had scattered, so he prepared very little defense against the enemy. Shi Chao confronted Yue on 9 September, and defeated him heavily at the Battle of Dangyin. The emperor was wounded in battle and captured by Shi Chao. Yue fled to Xiapi and then to his fief in Donghai, while Yue's allies retreated back to Luoyang with Sima Tan.

With Yue defeated, Ying then planned to eliminate the Inspector of You province, Wang Jun, a former partisan of Empress Jia who refused to join the coalition against Sima Lun. Ying sent a general to assassinate him, but when the plot was uncovered, Wang Jun rebelled and allied himself with the Inspector of Bing province, Sima Teng, a brother of Sima Yue. Wang Jun's army consisted of many Xianbei and Wuhuan soldiers due to his alliances with the neighbouring nomadic tribes. In response, Ying sent generals out to oppose him.

Yong sent Zhang Fang to assist Sima Ying, but after learning Emperor Hui was in Ye, he ordered Zhang Fang to occupy Luoyang instead. Sima Tan was still holding the capital, although real power laid with his general, Shangguan Si (上官巳). Zhang Fang fought Shangguan Si and dealt him a great defeat, forcing them back into the city. One night, Tan led his troops to attack Shangguan Si and ousted him from Luoyang. He then welcomed Zhang Fang into Luoyang, but Zhang Fang soon depose him and Yang Xianrong.[19]

Ying had a general named, Liu Yuan, a sinicized Xiongnu noble who he accepted an offer from to rally the Xiongnu people of Bing province to resist Wang Jun's forces. However, after allowing him to return to Bing, Liu Yuan took the opportunity to name himself "King of Han" and made a bid for the imperial throne as a legitimate successor to the Han dynasty.[20] In late Cao Wei or early Jin times, the Southern Xiongnu nobles claimed that they had Han Dynasty ancestry as well—through marriage alliance (Heqin) which many princesses of Han dynasty married many chanyus (ruler of Xiongnu) throughout different period in Xiongnu history and therefore changed their family name to Liu, the same name as the Han imperial clan. Appealing to the Southern Xiongnu, who numbered less than 20,000, Liu Yuan convinced them to join him and reclaim the legacy of their forebears. Soon his forces swelled to over 50,000.[19]

Wang Jun and Sima Teng won a series of victory on their way to Ye. When their forces reached the outskirts of the city, the people of Ye were terrified and began fleeing. Lu Zhi urged Ying to use his remaining 15,000 armored troops to escort Emperor Hui of Jin back to Luoyang, but on the morning of their departure, the troops deserted. As there were no horses and porters, Ying and Emperor Hui had to flee on calf-drawn carts. Wang Jun's forces entered Ye and sacked the city. His Xianbei troops partook in mass pillaging while he ordered to execute anyone who was hiding their possessions for them to take. As a result, around 8,000 people were killed and their bodies were dumped into the Yi River. Wang Jun then left Ye and returned to his base in Ji.

In southwest China, Li Xiong, the son of Li Te, created the Ba-Di state of Cheng Han in 304. South of the Changjiang, despite his rebellion spilling over to multiple provinces, Jin forces were able defeat and capture Zhang Chang.[21]

Ying's party managed to reach Luoyang, but with very little troops, Zhang Fang was able to dominate him and take possession of Emperor Hui. For a brief period, Zhang Fang was in charge of state affairs. He remained with the in Luoyang for a few more months, but his soldiers were becoming restless and were suggesting him to move the emperor to Chang'an. On 14 December 304, Zhang Fang forced Emperor Hui to stay at the ramparts he built during his war with Sima Ai. With the emperor away, Zhang Fang's men looted the palaces in the capital. He also planned to burn them down as well, but was persuaded not to by Lu Zhi.

Three days later, Zhang Fang brought Emperor Hui, Ying and the others to Chang'an. Yong welcomed the emperor and placed him under his care. On 4 February 305, Yong issued an edict deposing Ying as Crown Prince and handed the position over to the Prince of Yuzhang, Sima Chi.

Later, Sima Yong appointed Sima Yue as the Grand Tutor in hopes of resolving the conflict between their sides. Yong also granted Yue's brothers, Sima Lue and Sima Mo military command in Luoyang and over Ji province respectively. Yue declined his office, but for the time being, it appeared that the two sides had reached an agreement. Since Wang Jun had left Ye, Yue sent Mo to guard the city, while Lue remained in his position as Commander over Qing province. Seeing that many parts of the empire have been devastated by warfare and rebellion, Yong issued an edict encouraging everyone to settle for peace. In another edict, he made himself Commander of all imperial military forces.

Although Emperor Hui was now in Chang’an, the influential ministers, Xun Fan, Liu Tun, and Zhou Fu, were left behind in Luoyang to run a separate court. Thus, there were two courts governing the empire, and Chang’an was referred to as the “Western Court” (西臺) while Luoyang was referred to as the “Eastern Court” (東臺). The Eastern Court reinstated Yang Xianrong as the empress, but the following year, she was deposed by Zhang Fang.

Since 303, Huangfu Zhong had resisted Sima Yong from Jicheng, even well after Sima Ai was executed. Around this time, he sent his son Huangfu Chang (皇甫昌) to meet with Sima Yue and request reinforcements. Yue denied his request, as he had only made peace with Yong, so Chang went to Luoyang with a forged edict from Yue to entice a campaign against Yong. After restoring Yang Xianrong as empress, he claimed that she had ordered the officials in Luoyang to attack Zhang Fang and return the emperor to the old capital. They were initially willing to participate, but after learning that the edict was fabricated, they had Chang killed. Soon, the people of Jicheng killed Huangfu Zhong before surrendering, and Yang Xianrong was deposed again.

In autumn 305, Sima Yue sent out a proclaimation throughout the regions east of Luoyang calling for a campaign against Yong. He cited that Zhang Fang had forcibly moved Emperor Hui to Chang'an and aimed to bring him back to Luoyang. His brothers and several other prominent governors such as Wang Jun and Sima Xiao all joined him, which greatly disturbed Yong. Yue also began handing out new appointments to his allies without the emperor's consent, but when he tried to transfer the Inspector of Yu province, Liu Qiao and the Inspector of Yan province, Sima Mao, they defected to Yong's side with the latter accusing Yue of overstepping his authority.

In the Hebei region, where Sima Ying was still regarded as a revered figure, the people were upset by Yong's decision to remove him from power. Ying's general, Gongshi Fan took advantage of their resentment and rebelled. Among the people who joined him were a shepherd, Ji Sang and a former Jie slave, Shi Le.[22] To quell his rebellion, Yong sent Sima Ying and Lu Zhi with 1,000 troops to Ye.

Liu Qiao sent his troops to block Yue from advancing west at Xiao County. On 20 November, Yong appointed Zhang Fang commander of 100,000 troops and sent him to assist Liu Qiao. Soon, Liu Qiao captured Xuchang from Sima Xiao, prompting him to flee to Ji province. Due to the early setbacks, a general of Yue, Chen Min, received permission to go east to recruit more soldiers. However, once there, Chen Min instead rebelled and took control of the Jiangnan region.[23]

In Luoyang, another rebellion broke out which saw Yang Xianrong restored as empress, but it was quickly defeated and she was deposed once more. Seeing that she was being used as a political asset against him, Yong forged an edict from the emperor ordering the Eastern Court to execute her. However, he was opposed by Liu Tun and the others in Luoyang, and after failing to arrest Liu Tun, he changed his mind.

In Ji province, Sima Xiao received some elite Xianbei and Wuhuan cavalry forces from Wang Jun. With them, Xiao and his general, Liu Kun launched a successful counterattack on Yong and Liu Qiao's forces. Xiao's forces routed Sima Mao at Linqiu (廩丘, in present-day Puyang, Henan) and forced him to flee back to his fief in Dongping. Then, they won a great victory over Liu Qiao at Qiao Commandery, causing his army to collapse.

Early in 306, the administrator, Liu Bogen (劉柏根) declared himself the Duke of Jian and briefly took over Qing province. He was swiftly defeated, but one of his followers, Wang Mi, escaped to Mount Zhangguang (長廣山; in present-day Pingdu, Shandong) and became a bandit, quickly gaining followers under his wing.

Following Liu Qiao's defeat, Yong was desperate settle for peace with Yue, but Zhang Fang advised him to keep fighting. In response, Yong had Zhang Fang executed and sent his head to Yue as part of a peace offer. Yue ignored it and used the head to convince Yong's other generals to surrender. He then sent his generals with Wang Jun's Xianbei troops towards Chang'an. Unable to stop them, Yong fled alone to Mount Taibai as the Xianbei soldiers sacked the city, killing around 20,000 people. On 11 June 306, Emperor Hui was sent back to Luoyang and arrived on 28 June. Yong soon returned and recaptured Chang'an, but at this point, the city was the only stronghold he had in control.[24]

Sima Yue was the last of the so-called Eight Princes to take control over the imperial court. After receiving Emperor Hui, Yue was appointed Grand Tutor and Manager of the Affairs of the Masters of Writing. On 8 January 307, Emperor Hui died after consuming poisoned bread. It is not clear if Yue was involved in his death. Emperor Hui was succeeded by his brother, Sima Chi, later known as Emperor Huai.

Emperor Huai was regarded as an intelligent man, and compared to Emperor Hui, he had more say and was more active in handling state affairs. Yue still retained considerable influence over the state, but he was now unable to exercise the similar authority he had under Emperor Hui. Later on, he became Prime Minister on 5 February 308, but he remained deeply suspicious of the new emperor's capabilities.

Previously, Sima Ying had been ordered to garrison at Ye to appease Gongshi Fan's rebels. However, he was unable to get through Luoyang due to Yue's forces and decided to return towards Chang'an. Following Yong's defeat, Yue issued an edict calling for Ying's arrest. Ying and Lu Zhi attempted to flee southward but were intercepted. They then planned to join Gongshi Fan, but Sima Xiao caught and apprehended the prince in Ye.

Around November or December 306, Sima Xiao died of natural causes. Xiao's advisor Liu Yu was concern that his death would encourage the people of Ye to rebel with Ying as their leader. Therefore, he forged a false edict ordering the execution of Ying and killed him during the night. Lu Zhi buried Ying and took up a staff position with Sima Yue. Gongshi Fan was also defeated and killed by Yue's general, Gou Xi, but his subordinates, Ji Sang and Shi Le, escaped.

Sima Yong held out in Chang'an until around December 306 or January 307. Around this time, Yue sought for peace by issuing an edict to appoint Yong as Minister Over the Masses. Yong believed that Yue's intentions were genuine, and so he left Chang'an for Luoyang. However, along the way, he was intercepted by a general of Sima Mo at Xin'an, who had him strangled in his carriage.[24][25]

• Sima's family tree of the Western Jin dynasty