War of the Eight Princes facts for kids

The War of the Eight Princes was a series of power struggles and civil wars in ancient China. These conflicts happened among powerful princes of the Western Jin dynasty. It took place from 291 to 306 AD. The main reason for these wars was who would control the empire. This was especially important because the emperor, Emperor Hui of Jin, had a developmental disability.

The name "War of the Eight Princes" can be a bit misleading. It wasn't one long war. Instead, it was many short, intense fights with peaceful times in between. Not all eight princes were fighting on the same side at any one time. The first conflicts were more like political tricks and sudden takeovers, not full-scale wars. A better name might be "Disorder of the Eight Kings."

At first, the fights were small and happened mostly in the capital city, Luoyang. But as more princes joined, the war grew much bigger. These civil wars made the empire weak. This allowed tribal groups, who had moved into China, to rebel. By the end, the war had badly damaged northern China. It led to a period called the Sixteen Kingdoms, causing many years of fighting.

Who Were the Eight Princes?

Many princes were involved in this conflict. But eight main princes played the biggest roles:

Other important people included Emperor Hui of Jin, his co-ruler Yang Jun, Empress Dowager Yang Zhi, Empress Jia Nanfeng, and the senior minister Wei Guan. It's good to know that the princes' titles didn't always mean they operated from those places. For example, Sima Ying was the Prince of Chengdu, but he mostly stayed in Ye during the war.

Family Connections of the Princes

The family tree below shows how the eight princes were related to each other and to the emperors.

Why the War Started

Map showing the Eight Princes and their fiefs.

The Jin dynasty was founded by Sima Yan, also known as Emperor Wu. He learned from past mistakes of the Cao Wei state. That state had kept its princes from having military power. This made it easy for powerful families to take control. So, Emperor Wu decided to give his own family members, like uncles and cousins, more power. They were given land and armies. This was meant to protect the Jin dynasty.

However, Emperor Wu had a problem with his son, Sima Zhong. Sima Zhong, who became Emperor Hui, had a developmental disability. Some officials wanted a more capable brother to be the next emperor. But Emperor Wu stuck to the traditional rules. He also hoped his grandson, Sima Yu, would be a strong leader after Sima Zhong.

Emperor Wu thought his family would work together to protect the dynasty. But after Emperor Hui became emperor, the princes became selfish. They started fighting each other for control. This war happened at the same time as a big uprising by tribal groups. These groups had moved into China over time. The princes' fighting made the Jin empire weak. This allowed these groups to break away and form their own states. This began the Sixteen Kingdoms period.

First Conflicts: The Yang Family (290-291)

Emperor Hui Takes the Throne

In 289, Emperor Wu became very ill. He thought about making his father-in-law, Yang Jun, and his uncle, Sima Liang, co-rulers for his son, Sima Zhong. But Yang Jun wanted all the power for himself. He sent Sima Liang away and forced another official, Wei Guan, to retire. Yang Jun also hid the emperor's real will. Instead, his daughter, Empress Yang Zhi, issued a new order. It said her father, Yang Jun, would be the only ruler.

Emperor Wu died on May 16, 290. Sima Zhong became Emperor Hui. Yang Jun became the main ruler, and Yang Zhi became Empress Dowager. But many officials didn't like Yang Jun. He tried to kill Sima Liang and refused good advice. Meanwhile, the new empress, Jia Nanfeng, was also unhappy. She had very little power because of Yang Jun and the Empress Dowager.

The Fall of the Yang Family

Empress Jia decided to act. She asked Sima Liang and Sima Wei for help to overthrow Yang Jun. Sima Liang was hesitant, but Sima Wei agreed. He brought his troops to the capital, Luoyang. On April 23, 291, Empress Jia and her allies sent out an order to remove Yang Jun. They surrounded his home. Yang Jun was surprised and didn't know what to do. Empress Dowager Yang Zhi tried to get soldiers to turn against Empress Jia, but she failed. This made her look guilty.

Soon, soldiers attacked Yang Jun's home and set it on fire. His soldiers were defeated. Yang Jun was killed trying to escape. His family and supporters were also arrested and executed. Empress Dowager Yang Zhi was spared. But she was kept in the palace until she died in 292.

Prince of Ru'nan, Sima Liang (291)

On May 4, 291, Sima Liang and Wei Guan became the new regents for Emperor Hui. Sima Liang started giving out many new jobs and titles. He wanted to gain more support. At the same time, Empress Jia also put her family and friends in powerful positions.

Liang and Wei Guan were worried about Sima Wei. He was known for being violent. They tried to take away his military power and send him back to his land. But Sima Wei fought back. He worked with Empress Jia. He told her that Liang and Wei Guan were planning to overthrow her. Empress Jia then issued an order from the emperor to remove Liang and Wei Guan. Sima Wei secretly changed the order. He made himself the commander of all military forces. On July 26, 291, he sent his soldiers to arrest Liang and Wei Guan in Luoyang. Both men were killed without fighting back.

Prince of Chu, Sima Wei (291)

Because of the changed order, Sima Wei now had a lot of military power. After Liang and Wei Guan died, people told him to get rid of Empress Jia's powerful relatives. But Wei was unsure. In Empress Jia's group, a minister named Zhang Hua told her to punish Wei for killing the emperor's regents. Just one day after Liang's death, Empress Jia sent her troops against Wei. She also spread rumors that Wei's order was fake. His soldiers left him. Wei was captured and executed.

Empress Jia's Rule (291–300)

Power Behind the Throne

For the next nine years, Empress Jia ruled the Jin dynasty. She made decisions in the emperor's name. She gave power to her closest family, like Jia Mi and Guo Zhang. All important matters went to her. She would then approve or reject decisions made by her chosen officials. Even though some ministers tried to keep the government working, Empress Jia's court was full of corruption. People started hearing rumors about Empress Jia's bad behavior. This caused a lot of unhappiness.

Empress Jia also made some changes that affected the next part of the war. In 296, a big rebellion started in western provinces. It was led by Qi Wannian. The Prince of Zhao, Sima Lun, failed to stop it. So, he was called back to Luoyang. Later, the Prince of Chengdu, Sima Ying, was sent away. This happened after he argued with Jia Mi about how the Crown Prince, Sima Yu, was being treated.

Sima Lun's Takeover

Empress Jia saw the Crown Prince, Sima Yu, as a threat. He was not her own son. In 299, she had him arrested.

Sima Lun was the prince's tutor. He had become close to Empress Jia. He also commanded some troops in the capital. Many officials were angry about Yu's arrest. They asked Lun to use his military power to overthrow Empress Jia.

Lun wanted to betray the empress. But his advisor told him to wait until Yu was gone. He argued that if Lun acted too soon, Yu might become emperor and punish Lun. So, with Lun's encouragement, Empress Jia had Yu killed. Then, Lun claimed he had an order from Emperor Hui to remove her. On May 7, 300, he arrested Empress Jia. He later forced her to end her life. He also executed many of her supporters.

Prince of Zhao, Sima Lun (300–301)

Location of the remaining six of the Eight Princes at the time of Sima Lun's usurpation in February 301.

Sima Lun became the new regent for Emperor Hui. But he gave most of his power to his advisor. Lun and his advisor planned to take the throne for themselves. They gave high positions and titles to their family and friends. They also tried to gain public support.

In late 300, another prince rebelled against Lun. Lun almost died in the fighting. But one of his supporters tricked and killed the rebel prince. This rebellion gave Lun an excuse to get rid of his rivals. Meanwhile, the Prince of Qi, Sima Jiong, was unhappy with his position. Lun sent him away to another city.

After this rebellion, Lun was given special honors. The next year, he claimed that his father's spirit told him to move into the emperor's palace. He then faked an order saying Emperor Hui was giving up the throne. On February 3, 301, Sima Lun took the throne for himself.

Three Princes Unite

Soon after Lun took the throne, Sima Jiong rebelled. He called on others to fight against Sima Lun. The most important prince to join him was Sima Ying. Ying was described as handsome but not very smart. However, he listened to his advisor and gathered many people to his side. About 200,000 troops joined him, including forces from Sima Ai. In another city, Sima Yong first sent troops to support Lun. But when he saw how large the rebel forces were, he joined them instead. Because of their strong bases and large armies, Jiong, Ying, and Yong were called the "Three Princes."

Lun sent armies to stop them. One of Lun's generals defeated Jiong several times. But then a false report made Lun recall some of his troops. Jiong then turned the tide and pushed back Lun's general.

Another of Lun's armies fought Sima Ying. Ying's forces were badly defeated at first. But Ying's advisor told him to launch a surprise attack. Lun's generals were overconfident and unprepared. Ying rallied his troops and attacked, crushing Lun's forces. Ying's army was the first to march towards Luoyang.

As the rebel armies got closer, officials in the capital started turning against Lun. On May 30, 301, a general arrested Lun in the palace. Lun's advisor and many supporters were also captured and executed. Lun was forced to take his own life.

Emperor Hui was put back on the throne. Ying reached the capital first, followed by Yong. Jiong was still fighting, so Ying sent soldiers to help him. After Jiong's enemies surrendered, Jiong entered the capital with a huge army.

Prince of Qi, Sima Jiong (301–303)

Becoming Regent

On August 11, 301, Sima Jiong received special honors and became the regent for Emperor Hui. Jiong wanted to share power with Sima Ying. But Ying's advisor told him to return to his base to care for his mother. So Ying left all the responsibility to Jiong. At his base, Ying made popular changes to win over the people. He sent grain to areas hit by famine. He also arranged funerals for fallen soldiers and buried many of Sima Lun's troops. These were all ideas from his advisor.

In mid-302, the last person in the Crown Prince's family line died. This caused confusion about who would be next in line. Sima Jiong named the emperor's nephew as the new Crown Prince. During his rule, Jiong upset many officials. He was arrogant and spent too much money. He rarely visited the emperor or attended meetings.

An official named Wang Bao was worried about the princes' military power. He believed they would use it against Jiong. Wang Bao urged Jiong to send the princes back to their lands. He also suggested sharing power with Sima Ying. Jiong was almost convinced. But when Sima Ai found out, he told Jiong to reject the plan. Wang Bao was then executed.

Plot Against Jiong

Jiong wanted to appoint one of Sima Yong's chief officers to a military role. This officer was afraid to accept because he had an enemy in Jiong's circle. He fled back to Yong and planned a rebellion with him. Yong was told to team up with Sima Ying. He also planned to force Sima Ai, who was in Luoyang, to join. This would make Jiong execute Ai, giving a reason to overthrow Jiong.

In January 303, Yong rebelled. Ying was tempted to join him. Yong sent his generals to fight Jiong. They also sent an order for Ai to attack Jiong. Believing Ai was involved, Jiong sent troops to kill him. Ai fled to the imperial palace for safety. There, he defended the palace against Jiong for three days. He kept Emperor Hui with him. On January 27, Jiong's own officers betrayed him. He was captured and killed.

Prince of Changsha, Sima Ai (303–304)

Controlling the Court

Sima Ai took control of the capital. But he gave authority to his brother, Sima Ying. This outcome upset Yong and Ying, as it stopped their original plans. Ying was especially unhappy because he had limited power. The relationship between the brothers worsened.

Ai's government struggled to handle rebellions. In the southwest, a rebellion continued even after its leader died. Along the Changjiang river, another rebellion started. When the court asked Sima Yong to fight these rebels, he refused. Ai also refused to let another prince send his troops. Ai suspected this prince was working with Ying. This prince was later killed by rebels.

Siege of Luoyang

After a failed assassination attempt, Yong prepared his troops for war. Sima Ying was on his way to fight a rebellion. But hearing about the situation, he joined Yong instead. In late 303, Yong sent an army of 70,000 to attack the capital. Ying also sent a huge army of 200,000 troops.

Surprisingly, Emperor Hui led his own troops to help Sima Ai defend Luoyang. Ai's forces defeated Ying's army outside the city. Ai then personally led Emperor Hui and confronted a large enemy army. Ai's cavalry charged, heavily defeating them. Many enemy officers were killed.

Ai then moved west to face Yong's general. The emperor's presence caused panic among the enemy. They were badly defeated. Yong's general secretly built defenses during the night. Ai attacked them but failed.

Ai's officials tried to make peace with Ying. But Ying refused unless Ai executed his advisor, which Ai would not do.

Yong's general cut off Luoyang's water supply. Ai tried to get another general to defect from Yong and attack his base. He also sent an order from the emperor to get generals to disband. But his messenger was captured and killed.

Ai held out in Luoyang until March 304. Yong's general was about to give up. But a minister, Sima Yue, feared Ai would not win in the long run. On March 17, he and other officials kidnapped Ai. The next day, they surrendered to the enemy. But the capital troops regretted surrendering. They secretly planned to free Ai. Fearing this, Yue sent Ai to Yong's general, who had Ai killed by fire.

Prince of Chengdu, Sima Ying (304–305)

Becoming Crown Prince

After Sima Ai's death, Sima Ying made himself Prime Minister. He promoted Sima Yue to a high position. Despite his new role, Ying kept Emperor Hui in Luoyang. He left an army there and returned to his base. In April 304, he imprisoned the empress and removed his nephew from being Crown Prince. On May 1, Ying was made Crown Prince. His power was said to be like that of Cao Cao in the past. Sima Yong was also given a high military role. As Crown Prince, Ying became more arrogant and spent a lot of money. He showed favoritism, which made some supporters unhappy.

Battle of Dangyin

On August 17, 304, Sima Yue rebelled in Luoyang. He brought back the empress and the former Crown Prince. He gathered a huge army and marched on Ying's capital. He brought Emperor Hui with him. Along the way, Yue was wrongly told that Ying's soldiers had scattered. So he was unprepared. Ying's general attacked Yue on September 9. He heavily defeated Yue at the Battle of Dangyin. The emperor was wounded and captured. Yue fled, and his allies retreated to Luoyang.

Sack of Ye

With Yue defeated, Ying planned to deal with a governor who had refused to join him earlier. Ying sent a general to kill him. But the plot was discovered. The governor rebelled and allied with Sima Teng, Yue's brother. Their army included many tribal soldiers. Ying sent generals to fight them.

Yong sent his general to help Sima Ying. But after learning Emperor Hui was with Ying, he ordered his general to occupy Luoyang instead. The capital was still held by the former Crown Prince. Yong's general fought and defeated him. He then welcomed Yong's general into Luoyang. But Yong's general soon removed the Crown Prince and the empress.

Ying had allowed a tribal noble, Liu Yuan, to return to his home. Liu Yuan was supposed to gather his people to fight Ying's enemies. But Liu Yuan instead declared himself "King of Han." He claimed to be a rightful successor to the Han dynasty. His forces quickly grew to over 50,000.

The rebel forces led by Wang Jun and Sima Teng won battles on their way to Ye. When they reached the city, people were terrified and fled. Ying's advisor urged him to escort Emperor Hui back to Luoyang. But on the morning they were supposed to leave, the troops deserted. Ying and Emperor Hui had to flee in slow, calf-drawn carts. Wang Jun's forces entered Ye and looted the city.

In southwest China, the son of a rebel leader created his own state in 304. In the south, another rebellion was defeated.

Captivity in Luoyang

Ying and Emperor Hui managed to reach Luoyang. But with very few troops, Yong's general took control of them. For a short time, Yong's general was in charge. He stayed in Luoyang for a few months. But his soldiers wanted to move the emperor to Chang'an. On December 14, 304, Yong's general forced Emperor Hui to stay at his military camp. With the emperor away, his men looted the palaces in the capital. He also planned to burn them down but was convinced not to.

Three days later, Yong's general brought Emperor Hui, Ying, and others to Chang'an. Yong welcomed the emperor and took care of him. On February 4, 305, Yong issued an order removing Ying as Crown Prince. He gave the position to another prince.

Prince of Hejian, Sima Yong (305–306)

Commander-in-Chief

Later, Sima Yong appointed Sima Yue to a high position. He hoped to end the conflict between them. Yong also gave Yue's brothers military commands. Yue refused his new office. But for a while, it seemed they had reached an agreement. Yong issued an order encouraging peace. He also made himself the commander of all imperial military forces.

Even though Emperor Hui was in Chang'an, important officials were left in Luoyang. They ran a separate court. So, there were two courts governing the empire. Chang'an was called the "Western Court," and Luoyang was the "Eastern Court." The Eastern Court brought back the empress, but she was later removed again.

Eastern Army Coalition

In late 305, Sima Yue sent out a call for war against Yong. He said Yong's general had forced Emperor Hui to Chang'an. He wanted to bring the emperor back to Luoyang. His brothers and other powerful governors joined him. This worried Yong. Yue also started giving out new jobs without the emperor's permission. But when he tried to move two governors, they joined Yong instead.

In the Hebei region, people were upset that Yong had removed Sima Ying from power. Ying's general took advantage of this and rebelled. To stop him, Yong sent Sima Ying and his advisor to Ye.

Yong's general blocked Yue from moving west. On November 20, Yong appointed his general commander of 100,000 troops. He sent him to help block Yue. Soon, Yong's general captured a city, forcing another prince to flee. Because of these early problems, one of Yue's generals went east to recruit more soldiers. But once there, he rebelled and took control of the southern region.

In Luoyang, another rebellion broke out. The empress was restored but quickly removed again. Yong tried to order her execution, but officials in Luoyang refused.

In the north, Sima Xiao received elite cavalry from another general. With them, Xiao and his general launched a successful counterattack. They defeated Yong's forces.

Early in 306, a local leader declared himself duke. He briefly took over a province. He was quickly defeated. But one of his followers escaped and became a bandit. He quickly gained many followers.

After a defeat, Yong was desperate for peace with Yue. But his general advised him to keep fighting. In response, Yong had his general executed. He sent his head to Yue as a peace offering. Yue ignored it. He used the head to convince Yong's other generals to surrender. He then sent his generals with tribal troops towards Chang'an. Yong could not stop them. He fled alone as the tribal soldiers looted the city, killing many people. On June 11, 306, Emperor Hui was sent back to Luoyang. Yong soon returned and recaptured Chang'an. But by this point, it was his only stronghold.

Conclusion: Prince of Donghai, Sima Yue (306–311)

Death of Emperor Hui

Sima Yue was the last of the Eight Princes to control the imperial court. After receiving Emperor Hui, Yue was given high positions. On January 8, 307, Emperor Hui died after eating poisoned bread. It is not clear if Yue was involved. Emperor Hui was succeeded by his brother, Sima Chi, who became Emperor Huai.

Emperor Huai was considered intelligent. Compared to Emperor Hui, he was more active in state affairs. Yue supported Huai as emperor. He rejected calls to replace him with a child prince and even had that prince executed. Yet, Yue was also worried about the new emperor's abilities. He was likely insecure about his own position after so many coups. Yue left the capital shortly after Huai became emperor. He became Prime Minister on February 5, 308.

Deaths of Sima Ying and Sima Yong

Earlier, Sima Ying had been ordered to stay in Ye to calm rebels. But he couldn't get through Luoyang because of Yue's forces. He decided to return towards Chang'an. After Yong's defeat, Yue ordered Ying's arrest. Ying tried to flee south but was caught. He was then killed. His advisor buried him.

Sima Yong held out in Chang'an until late 306 or early 307. Yue tried to make peace by offering Yong a high position. Yong believed Yue and left Chang'an for Luoyang. But on the way, he was stopped by a general and killed in his carriage.

What Happened Next

317 AD

Sima Yue's victory didn't last long. He now had to deal with many rebellions across the empire. Some rebellions were put down. But others, led by figures like Shi Le and Wang Mi, joined Liu Yuan's state. Together, they took over most of northern China. In Sichuan, Jin forces failed to defeat another state.

Sima Yue returned to Luoyang in 309. He took steps to control the court more tightly. He had the emperor's favorite officials arrested and executed. He also replaced the palace guards with his own soldiers. Around this time, Luoyang was hit by famine and attacked twice. Yue decided to march out with the imperial army to fight. Emperor Huai was left behind in the capital.

This decision broke their relationship. Huai started plotting to remove Yue. Their plans were discovered. Yue wanted to attack his second-in-command, but he became too stressed and died on April 23, 311. The imperial army was unsure what to do. They chose a temporary leader and decided to hold Yue's funeral. However, the funeral procession was caught by Shi Le's forces and defeated. The imperial army was destroyed. With the main Jin army gone, tribal forces attacked Luoyang. They looted the city and captured Emperor Huai on July 13, 311. This event is known as the Disaster of Yongjia.

The Western Jin dynasty lasted only five more years. A new emperor tried to restore the empire in Chang'an. But that too fell by the end of 316. The Sima family eventually re-established the Eastern Jin dynasty in southern China. Within four years of his victory, Sima Yue had been overwhelmed by rebellions and politics. Five years after his death, both capitals were lost. Most of northern China fell under the rule of many short-lived states. This period is known as the Sixteen Kingdoms.

See also

• The Eight Princes' family tree
• Sima clan family trees - including some of the Eight Princes
• Upheaval of the Five Barbarians