In October of the first year of Hanwang (206 BC), Liu Bang became king in Guanzhong after the Qin Dynasty was destroyed. In December, Xiang Yu invaded Hanguguan to destroy Liu Bangjun. Knowing the defeat, Liu Bang went to Hong Men (now northeast of Lintong, Shaanxi) to apologize. Soon, Xiang Yu entered Xianyang. In the spring, Xiang Yu regarded Chu Huaiwang as the righteous emperor on the surface, but actually sent him to the south of the Yangtze River, where he became the overlord of the land of Xi, the capital of Pengcheng (now Xuzhou, Jiangsu Province), and at the same time enfeoffed 18 vassal, named Liu Bang as Hanwang, and commanded Bashu and Hanzhong, and deliberately appointed Qin generals Zhang Han, Sima Xin and Dong Kun as Wang Sai and Zhaiwang. Liu bang had to submit to humiliation and accept the title. In April, he led the troops into Hanzhong and burned the plank road (the road paved with boards on the cliff), indicating that he had no intention of sending troops to paralyze Xiang Yu again. Xiang Yu also returned to the East with a great army. In May and June, Tian Rong, a descendant of Qi nobles, was dissatisfied with the enfeoffment, drove away the King of Qi, killed the King of Jiaodong, and established himself as the King of Qi. Liu Bang took advantage of the chaos to return to Guanzhong, defeated Zhang Han, forced Sima Xin and Dong Kun to land, and tricked Xiang Yu into believing that he was satisfied with Guanzhong and would never move eastward again. Xiang Yu safely attacked Tian Rong, and did not strengthen the prevention of the West. In October, Liu Bangdong invaded, worshipped Han Xin as a general, built a plank road, and secretly crossed Chencang (now east of Baoji City, Shaanxi Province), saying that the nominal emperor sent someone to contact the governors and publicly denounced Xiang Yu, which opened the prelude to the Chu-Han War.

The First Battle of Pengcheng: In April, Liu Bang took advantage of Xiang Yu's stay in Qi to lead the vassal army to capture Pengcheng in one fell swoop. Hearing this, Xiang Yu quickly led 30,000 chosen men to attack and annihilate more than 200,000 allied troops. Liu bang only led dozens of riders to escape, and the anti-Chu alliance collapsed.

Fight for: In May, Liu Bang arrived in Xingyang, repelled Chu's pursuers, stopped breathing, stabilized his position, reorganized the army, and relied on the Guanzhong base area and favorable terrain to fight against Xiang Yu for a long time. In June, Liu Bang sent troops to attack the waste hills and forced Zhang Han to commit suicide, which relieved his worries. Send someone to persuade Ying Bu to oppose Chu and contact Peng Yue to disturb Chu's rear; Han Xin was sent to open up the northern battlefield, attack Wei, destroy the generation, destroy Zhao and kill. In the winter of three years, Xiang Yu launched a counterattack and besieged Xingyang. The situation is very critical. Liu Bang used Chen Ping's double spy to make Xiang Yu doubt Fan Zeng, and forced Fan Zeng to return home in a rage. Liu Bangpa Ji Xin pretended to go to Chu Jun, surrendered, and fled Xingyang. Xiang Yu stepped up the siege of Xingyang and occupied the elevation.

In order to relieve the pressure of Chu army, Liu Bang led the army to lure Xiang Yu south through Wuguan, Wan (now Nanyang, Henan Province) and Ye (now south of Yexian County). In order to cooperate with the Han army, Han Xin also led an army to the north bank of the Yellow River to support Xingyang. Peng Yue attacked Xiapi (now south of Pixian County, Jiangsu Province). Xiang Yu was forced to lead the army to rescue, and Liu Bang took the opportunity to recover the elevation. In June, Xiang Yu launched a fierce offensive, withdrew from Xingyang, and then captured the elevation.

Liu bang ordered the Han army to stick to it in Gongxian county and stop the Chu army from advancing. At the same time, he ordered Han Xin to form a new army to attack Qi, and sent people to the hinterland of Chu to help Peng Yue attack Luoyang (now south of Shangqiu, Henan) and Waihuang, forcing Xiang Yu to rescue again. In October of four years, Liu regained it again.

After defeating Peng Yue, Xiang Yu failed to find the main force for the decisive battle of the Han army, so he stationed troops in Guangwu (now Rongyangbei) and confronted Liu Bang. Soon, Han Xin annihilated the Qi-Chu allied forces in the battle of Weishui, completed the strategic detour to the Chu flank, and sent Guan Ying to Pengcheng. Xiang Yu was caught between Scylla and Charybdis. So he made an alliance with Han and divided the world into two parts, with Chu in the east and Han in the west. In September, Xiang Yu led the troops eastward.

After the alliance between Chu and Han, Liu Bangben wanted to withdraw. Under the reminder of Sean and Chen Ping, he ordered the full pursuit of ChuJun. In October of five years, the two armies fought in Guling (now northwest of Huaiyang), and Xiang Yu won a small victory. Liu Bang wooed Han Xin, Peng Yue and Ying Bu. By honoring them, the Chu army suffered heavy losses in the next world war, forcing Xiang Yu to commit suicide in Wujiang (now Anhui county), and finally ending the four-year Chu-Han war. In February, Liu Bang proclaimed himself emperor and established the Han Dynasty.