# Chu–Han Contention

The Chu–Han Contention (楚漢相爭), also known as the Chu–Han War (楚漢戰爭), was an interregnum in Imperial China between the fall of the Qin dynasty and the establishment of the Han dynasty. After the Qin were overthrown by rebel forces in 206 BCE, the empire was divided into the Eighteen Kingdoms ruled by rebel leaders and former Qin generals according to Xiang Yu, the rebel leader. A civil war soon broke out, most prominently between two major contending powers – Xiang Yu and Liu Bang, who were respectively the rulers of the Chu and Han kingdoms. Some of the other kingdoms also waged war among themselves but these were largely insignificant compared to the main conflict between Chu and Han. The war ended with a Han victory at the Battle of Gaixia in 202 BCE, during which Xiang Yu committed suicide after having made a last stand. Liu subsequently proclaimed himself emperor of the newly established Han dynasty.

## Background

Towards the end of the Warring States period, the Qin state conquered the other six states – Han, Zhao, Yan, Wei, Chu and Qi – and unified China under the Qin dynasty in 221 BCE. Ying Zheng, the King of Qin, declared himself Shi Huangdi – the First Emperor. After his death in 210 BCE, an uprising broke out in 209, and lasted about five months until Qin forces crushed the rebellion.
Although the uprising had failed, other rebellions erupted consecutively over the next three years. The leaders of these rebellions were either pretenders to the thrones of the former six states conquered by Qin, or supporters of the pretenders. Among them, the most notable one was Xiang Yu, who descended from a family of Chu generals, and he wanted to restore the Chu state with King Huai II as its nominal ruler. Xiang Yu led Chu forces to victory over Qin forces at the Battle of Julu and declared himself "Hegemon-King of Western Chu". After the battle, he controlled nine commanderies in the former Liang and Chu territories, with the capital at Pengcheng (彭城; present-day Xuzhou, Jiangsu).
In the meantime, Liu Bang, another notable rebel leader who had initially joined Xiang Yu, had formed his own rebel group. While the bulk of the Qin forces were fighting against Xiang Yu at the Battle of Julu, Liu Bang led his forces into the Guanzhong region, the heartland of the Qin dynasty, facing minimal resistance along the way. In 206 BCE, the last Qin emperor, Ziying, surrendered the capital Xianyang to Liu Bang, bringing an end to the Qin dynasty. Liu Bang treated Ziying respectfully and forbade his followers from harming civilians and looting Xianyang. However, when Xiang Yu eventually arrived in the Guanzhong region, Liu Bang was pressured into ceding control of the region to Xiang Yu despite an earlier agreement between them that whoever occupied Guanzhong first would earn the title "King of Guanzhong".
After Xiang Yu took control of Xianyang, he allowed his troops to pillage and plunder the city and ordered the destruction of the Epang Palace. Xiang Yu also attempted to assassinate Liu Bang at the Feast at Swan Goose Gate but Liu Bang survived and escaped due to Xiang Yu's indecisiveness. Later, Xiang Yu forced Liu Bang to relocate from Guanzhong to the remote, underdeveloped Bashu region (present-day Chongqing and Sichuan).
Xiang Yu then divided the former Qin Empire into numerous vassal states, each ruled by either a rebel leader or a surrendered Qin general. The states were collectively known as the Eighteen Kingdoms, with the Kingdom of Chu as the nominal sovereign power over the other kingdoms. Xiang Yu also honoured King Huai II with a higher title, "Emperor Yi of Chu". Shortly after that, he exiled the figurehead emperor to Chen County (郴縣; present-day Chenzhou, Hunan), and secretly ordered Ying Bu, the King of Jiujiang, to intercept and assassinate Emperor Yi along the way.

## Initial stages

In 206 BCE, after the former Qin Empire was divided into the Eighteen Kingdoms, Liu Bang was made King of Han and relocated to the Bashu region (present-day Chongqing and Sichuan) along with 30,000 troops and thousands of civilians. Upon reaching his destination, Liu Bang ordered the destruction of the gallery roads leading into Bashu in order to trick Xiang Yu into believing that he had no intention of leaving Bashu, and as a precautionary move against any attack from outside Bashu.

### Rebellions in Qi and Zhao

Meanwhile, in the former Qi state, Tian Rong, a Qi noble, was unhappy with how the Qi territories had been split among three kingdoms – Qi, Jiaodong and Jibei, collectively known as the Three Qis – so he waged war against the other kingdoms. He killed Tian Shi, the King of Jiaodong, and Tian An, the King of Jibei. Tian Du, the King of Qi, was defeated by Tian Rong so he fled and joined Xiang Yu. Tian Rong gained control of the Three Qis and became the ruler of the Qi territories.
Tian Rong contacted Peng Yue and formed an alliance with him against Xiang Yu. At the same time, he sent troops to support Chen Yu, who had started a rebellion in the former state of Zhao. In 205 BCE, Chen Yu defeated Zhang Er, the King of Changshan, and seized control of his kingdom. Chen Yu then installed Zhao Xie, the King of Dai, as the new ruler of the Zhao territories.
Upon learning of the rebellions in Qi and Zhao, Xiang Yu led his forces to deal with the rebels.

### Han conquest of the Three Qins

While Xiang Yu was away, Liu Bang seized the opportunity to attack the territories in Guanzhong which were ruled by three former Qin generals and collectively known as the Three Qins. He sent Han Xin to pretend to repair the gallery roads leading from Bashu to the Three Qins in order to put the enemy off guard, while secretly taking another route through Chencang (present-day Chencang District, Baoji, Shaanxi) to get to the Three Qins. Han Xin took Zhang Han, the King of Yong, by surprise and defeated him in two consecutive battles.
Riding on the tide of victory, Liu Bang proceeded to conquer Longxi (the area in present-day Gansu located west of Mount Long), Beidi (eastern Gansu and Ningxia) and Shang (around present-day Yulin, Shaanxi). He also sent his men to fetch his family in Pei (present-day Xuzhou, Jiangsu) and bring them to him. Upon receiving news of Liu Bang's attacks, Xiang Yu sent an army to Yangjia (陽夏; present-day Taikang County, Henan) to block Liu Bang's forces; he also appointed Zheng Chang as the King of Hán to help him cover his flank.
Meanwhile, Zang Tu, the King of Yan, killed Han Guang, the King of Liaodong, seized his lands and proclaimed himself the ruler of the Yan territories.

### Battle of Pengcheng

In 205 BCE, after conquering the Three Qins in the Guanzhong region, Liu Bang advanced to the east of Hangu Pass to prepare for an attack on the Henan region. Sima Xin, the King of Sai, Dong Yi, the King of Di, and Shen Yang, the King of Henan, surrendered to Liu Bang. Zheng Chang, the King of Hán, refused to submit to Liu Bang, so Liu Bang sent Hán Xin to attack and defeat him. Liu Bang then replaced Zheng Chang with Hán Xin as the new King of Hán. Zhang Er, the former King of Changshan, joined Liu Bang after losing his domain to Zhao Xie and Chen Yu.
In April–May 205 BCE, Liu Bang attacked Henei with help from Wei Bao, the King of Western Wei. When Liu Bang received news that Xiang Yu had ordered the assassination of Emperor Yi, he held a memorial service for the emperor and accused Xiang Yu of committing regicide, using this incident as political propaganda to justify his war against Xiang Yu.
In May–June 205 BCE, Xiang Yu defeated Tian Rong at Chengyang (城陽; around present-day Ju County, Shandong). Tian Rong was killed while retreating to Pingyuan (around present-day northwestern Shandong). Although the Kingdom of Qi had surrendered, Xiang Yu still allowed his troops to plunder and loot the Qi territories. Tian Rong's younger brother, Tian Heng, made Tian Rong's son Tian Guang the new King of Qi, and continued to put up resistance against Xiang Yu.
Meanwhile, Liu Bang had mustered an army of about 560,000 with support from the kings who had surrendered to him. In September–October 205 BCE, the Chu capital, Pengcheng (彭城; present-day Xuzhou, Jiangsu), fell to a coalition force led by Liu Bang. When Xiang Yu received news that Liu Bang had occupied Pengcheng, he led 30,000 troops to retake Pengcheng. Liu Bang was caught off guard and his army suffered heavy casualties and his family members were captured by Chu forces. After the battle, Liu Bang lost his territorial gains in Chu and the support of his allies.

### Battle of Jingsuo

After their defeat at Pengcheng, the strength of the Han forces decreased drastically. Liu Bang's family members were captured by Xiang Yu's forces and kept as hostages. Many of the kings who had surrendered to Liu Bang earlier defected to Xiang Yu's side after Liu Bang's defeat. The rulers of Qi and Zhao also requested to make peace with Xiang Yu.
Upon reaching Xiayi (下邑; east of present-day Dangshan County, Anhui) which was guarded by his brother-in-law, Liu Bang reorganised his troops for a retreat. Meanwhile, Han Xin led reinforcements from Guanzhong into central China and defeated a Chu army between Jing County (京縣) and Suo Village (索亭), both in present-day Henan. He also put down a rebellion by Wang Wu and Cheng Chu – former Qin generals – and Shen Tu, the magistrate of Wei, and captured their base at Waihuang (外黃; in present-day Minquan County, Henan). He and Liu Bang reorganised the Han army and established strong Han garrisons in Xingyang and Chenggao. Han Xin also developed his plan to conquer northern China, with the aim that Xiang Yu would be too distracted by Liu Bang and his bases of Xingyang and Chenggao to properly counter Han Xin in the north, nor could he endanger his line of retreat by marching past Xingyang and Chenggao into Guanzhong.
Liu Bang then sent a messenger to meet Ying Bu, the King of Jiujiang, to persuade Ying Bu to support him. In November 205 BCE, after Han Xin's victory at the Battle of Jingxing, Ying Bu agreed to join Liu Bang and rebelled against Xiang Yu. Upon learning about it, Xiang Yu sent Long Ju to attack Ying Bu.
In July–August 205 BCE, Liu Bang named his son Liu Ying as his heir apparent and put him in charge of Yueyang (櫟陽; present-day Yanliang District, Xi'an). Shortly after, Han forces conquered Feiqiu (廢丘; present-day Xingping, Shaanxi), which was guarded by Zhang Han, who committed suicide after his defeat.
On another front, Ying Bu was unable to resist Long Ju's attacks so he gave up on his domain in Jiujiang and joined Liu Bang.

## Northern front
### Battle of Anyi

In 205 BCE, Wei Bao left Liu Bang on the pretext of visiting an ill relative and secretly returned to his domain. He pledged allegiance to Xiang Yu and rebelled against Liu Bang. Liu Bang sent Li Yiji to persuade Wei Bao to surrender but Wei Bao refused, so Liu Bang ordered Han Xin to attack Wei Bao.
Wei Bao stationed his army at Puban (蒲阪; present-day Yongji, Shanxi) and blocked the route to Linjin (臨晉; present-day Dali County, Shaanxi). Han Xin tricked Wei Bao into believing that he was planning to attack Linjin, while secretly sending a force from Xiayang (夏陽; present-day Hancheng, Shaanxi) to cross the river and attack Anyi (安邑; present-day Xia County, Shanxi).
In October–November 205 BCE, Wei Bao personally led an attack on Han Xin but lost the battle and was captured. When he surrendered, Liu Bang accepted his surrender and appointed him as a general. Within the same month, Han Xin attacked the Kingdom of Dai with support from Zhang Er, the former King of Changshan, scored a decisive victory, capturing the Dai chancellor Xia Shuo.

### Battle of Jingxing

After achieving victory over the Kingdom of Dai, Han Xin and Zhang Er attacked the Kingdom of Zhao at Jingxing Pass. Zhao Xie, the King of Zhao, and his chancellor, Chen Yu, led an army of 200,000 to resist the Han forces. Li Zuoche, a Zhao general, proposed a plan to trap Han Xin within ten days: he would lead 30,000 men to disrupt Han Xin's supply route and block his return route, while Chen Yu would defend the frontline firmly and prevent Han Xin from advancing. Chen Yu refused to follow Li Zuoche's plan.
The evening before the battle, Han Xin sent 2,000 horsemen, each carrying a flag of the Han army, to station near the Zhao camp. The next morning, Han Xin feigned defeat in a skirmish with Zhao forces and lured them to follow him, while his 2,000 men took advantage of the situation to capture the weakly defended Zhao camp. Meanwhile, the Zhao soldiers retreated after failing to conquer Han Xin's fort, and were surprised to see that their camp had been occupied by Han forces when they returned. The Zhao army fell into chaos and Han Xin seized the opportunity to launch a counterattack and scored a victory. Chen Yu was killed in action while Zhao Xie and Li Zuoche were captured.

### Battle of Wei River

In 204 BCE, after the Kingdom of Yan had surrendered to him, Liu Bang made Zhang Er the new King of Zhao. Xiang Yu constantly sent his forces to attack the Kingdom of Zhao, but Han Xin and Zhang Er managed to hold their ground. Xiang Yu then turned his attention towards Xingyang, where Liu Bang was stationed. Liu Bang was forced to retreat to Chenggao, but he eventually abandoned Chenggao and headed north of the Yellow River to where Han Xin was. In a surprise move, Liu Bang seized control over the troops under Han Xin's command and ordered Han Xin to attack the Kingdom of Qi.
Just as Han Xin was preparing to attack Qi, Liu Bang sent Li Yiji to persuade Tian Guang, the King of Qi, to surrender. However, Liu Bang had not informed Han Xin about what he had sent Li Yiji to do. Meanwhile, Tian Guang had decided to surrender to Liu Bang so he had pulled back his forces from Lixia (歷下; present-day Jinan, Shandong). However, as Han Xin did not know that Tian Guang had the intention of surrendering, he followed Kuai Tong's advice and launched an attack on the retreating Qi forces, conquering Lixia and attacking the Qi capital Linzi. Tian Guang thought that Li Yiji had lied to him to distract him from Han Xin's attacks, so he had Li Yiji boiled alive. Then, he retreated to Gaomi and requested aid from Xiang Yu. In the meantime, Han Xin conquered Linzi and continued to pursue the retreating Qi forces to Gaomi.
Xiang Yu sent Long Ju to lead 200,000 troops to help Tian Guang. After Han Xin defeated Long Ju in battle, Long Ju was advised to focus on strengthening his defences and getting Tian Guang to rally support from the fallen Qi territories. However, Long Ju decided not to heed the advice, and insisted on attacking Han Xin. On the night before the battle, Han Xin sent his men to dam the Wei River (濰水; in present-day Weifang, Shandong) with sandbags.
The next morning, after a skirmish with Chu forces, Han Xin feigned defeat and retreated to lure the enemy to follow him. After about a quarter of the Chu forces had crossed the river, Han Xin signalled to his men to open the dam. Many Chu soldiers drowned and Long Ju was isolated with only a fraction of his forces. Taking advantage of the situation, Han Xin launched a counterattack. Long Ju was killed in action and the rest of the Chu forces disintegrated as Han Xin continued pressing the attack. Tian Guang fled while Han Xin pursued the retreating Chu forces to Chengyang (城陽; near present-day Ju County, Shandong).
After his victory, Han Xin swiftly took control of the Qi territories and sent a messenger to Liu Bang, requesting that Liu Bang make him the new King of Qi. At the time, Liu Bang was under attack by Xiang Yu in Xingyang and was eagerly awaiting reinforcements from Han Xin. Initially, he was furious when he received Han Xin's request. However, he eventually acted on the advice of Zhang Liang and Chen Ping, and reluctantly approved Han Xin's request. At the same time, Xiang Yu felt worried after losing Long Ju, so he sent Wu She to incite Han Xin to rebel against Liu Bang and declare himself king. However, despite Kuai Tong's urging, Han Xin refused to betray Liu Bang. Han Xin later organised an army to move southward and attack Xiang Yu.

## Battle of Chenggao and the Treaty of Hong Canal

On the southern front, Liu Bang's forces started building supply routes from Xingyang to Aocang (敖倉; northwest of Xingyang, Henan). In 204 BCE, after sustaining losses from Chu attacks on the routes, Liu Bang's forces ran short of supplies so Liu Bang negotiated for peace with Xiang Yu and agreed to cede the lands east of Xingyang to Xiang Yu. Xiang Yu wanted to accept Liu Bang's offer, but Fan Zeng advised him to reject and use the opportunity to destroy Liu Bang. Xiang Yu changed his mind, pressed the attack on Xingyang and besieged Liu Bang's forces inside the city. Liu Bang heeded Chen Ping's suggestion to bribe Xiang Yu's men with 40,000 catties of gold for them to spread rumours that Fan Zeng had betrayed Xiang Yu. Xiang Yu fell for the ruse and dismissed Fan Zeng.
In late 204 BCE, while Xiang Yu was away suppressing the rebellion in Qi, Li Yiji had advised Liu Bang to use the opportunity to attack Xiang Yu. Liu Bang's forces conquered Chenggao and defeated the Chu army led by Cao Jiu near the Si River. Liu Bang's forces advanced further until they reached Guangwu (廣武; present-day Guangwu Town, Xingyang, Henan). Chu forces led by Zhongli Mo were trapped by Han forces at the east of Xingyang. Following Han Xin's victory at the Battle of Wei River, the Chu forces' morale fell and they ran short of supplies months later. Xiang Yu had no choice but to request to make peace with Liu Bang and release Liu Bang's family members, whom he had been holding hostage. Xiang Yu and Liu Bang then agreed to a ceasefire at the Treaty of Hong Canal, which divided China into east and west under the Chu and Han domains respectively.

## End of the war

In 203 BCE, while Xiang Yu was retreating eastward, Liu Bang, acting on the advice of Zhang Liang and Chen Ping, renounced the Treaty of Hong Canal and ordered an attack on Xiang Yu. He also requested assistance from Han Xin and Peng Yue to attack Xiang Yu simultaneously from three directions. However, as Han Xin and Peng Yue did not mobilise their troops, Liu Bang was defeated by Xiang Yu at Guling (固陵; south of present-day Taikang County, Henan) and forced to retreat and reinforce his defences. At the same time, he sent messengers to Han Xin and Peng Yue again, promising them land and titles if they joined him in attacking Xiang Yu.

### Battle of Gaixia

In December 203 BCE, Liu Bang, Han Xin and Peng Yue attacked Xiang Yu from three directions. Running low on supplies, Xiang Yu and his forces found themselves surrounded by Han forces in Gaixia (垓下; southeast of present-day Lingbi County, Anhui). Han Xin ordered his troops to sing Chu folk songs to create the impression that Chu territories had surrendered to Han forces and now many Chu men had joined the Han side. The morale of Xiang Yu's forces plummeted and many of his soldiers deserted.
Xiang Yu attempted to break out the siege and was left with only 28 men when he reached the northern bank of the Wu River (烏江; near present-day He County, Anhui). He made a last stand and managed to slay hundreds of Han soldiers before he was eventually overwhelmed and ended up committing suicide by slitting his throat.

## Aftermath

After Xiang Yu's death, the rest of the Chu forces surrendered to Liu Bang, and China was unified under Liu Bang's rule. Liu Bang granted Peng Yue, Ying Bu and Han Xin the titles of King of Liang, King of Huainan and King of Chu respectively. Months later, at the urging of his followers and vassals, Liu Bang declared himself emperor and established the Han dynasty as the ruling dynasty in China. The imperial capital was at Luoyang but later moved to Chang'an (present-day Xi'an, Shaanxi). Liu Bang made his wife Lü Zhi empress and his son Liu Ying crown prince.
Although Liu Bang initially handsomely rewarded those who helped him become emperor, he gradually became suspicious of them and started to doubt their loyalties. Han Xin was demoted from King of Chu to Marquis of Huaiyin in late 202 BCE, and was subsequently arrested and executed by Empress Lü in 196 BCE for allegedly plotting a rebellion with Chen Xi. In the same year, Liu Bang believed rumours that Peng Yue was also involved in the plot, so he demoted Peng Yue to the status of a commoner. Peng Yue and his family members were subsequently executed by Empress Lü.

## Cultural references

* In xiangqi, the middle section of the board that separates the players' sides is called the "Chu river and Han border" (楚河漢界). The red and black sides represent Han and Chu respectively.
* The Beijing opera The Hegemon-King Bids His Lady Farewell, also known as Farewell My Concubine, depicts the events of Xiang Yu's defeat at the Battle of Gaixia and his romance with Consort Yu.
* Two musical pieces for the pipa depict the Battle of Gaixia from the Han and Chu perspectives respectively – "Ambush from Ten Sides" (十面埋伏) and "The Hegemon-King Takes Off His Armour" (霸王卸甲).
* Some chengyu (Chinese idioms) and proverbs originated from the events of the Chu–Han contention, such as
** "Breaking cauldrons and sinking boats" (破釜沉舟), used to indicate one's determination to fight to the end, similar to burning one's boat and crossing the Rubicon. It originated from Xiang Yu's orders during the Battle of Julu when Chu forces launched a fierce attack on Qin forces.
** Feast at Swan Goose Gate (鴻門宴), used figuratively to refer to an ostensibly joyous occasion which is actually a dangerous trap. It originated from an incident in 206 BCE when Xiang Yu invited Liu Bang to attend a feast while secretly planning to assassinate Liu Bang during the feast. The saying "Xiang Zhuang performs a sword dance with his attention directed towards the Duke of Pei" (項莊舞劍，意在沛公) also originated from this event. It is used figuratively to refer to a person's action being a veiled attack on another person.
** "Pretending to repair the gallery roads while secretly passing through Chencang" (明修棧道，暗度陳倉), used to refer to disguising one's action with a more obvious action. It originated from Han Xin's strategy to attack the Three Qins.
** "Fighting a battle with one's back facing a river" (背水一戰), used to indicate one's determination to fight to the death. It originated from the Battle of Jingxing between Han and Zhao forces.
** "Ambush on ten sides" (十面埋伏), refers to a situation in which one is under siege. It originated from Han Xin's strategy to trap Xiang Yu during the Battle of Gaixia.
** "Surrounded by Chu songs" (四面楚歌), refers to one being surrounded by enemies on all sides. It originated from the Battle of Gaixia when the Han soldiers sang Chu folk songs to dampen the fighting spirit of the besieged Chu forces.