Xiang Yu rushed without stopping and finally arrived at Hongmen outside Xianyang city (present-day Hongmenbao Village, Xinfeng Town, Lintong District, Xi'an, Shaanxi), facing Liu Bang's camp at Bashang from a distance. Just then, a mid-level officer from Liu Bang's army came to Xiang Yu and reported that Liu Bang intended to declare himself king and had forbidden his men from killing the last Qin emperor, Ziying. Xiang Yu flew into a rage upon hearing this and vowed to capture Liu Bang. Fan Zeng also fanned the flames, making Xiang Yu even angrier, and he decided to attack Liu Bang's army the very next day.
The news quickly spread through Chu's camp, causing one man to panic: Xiang Yu's uncle, Xiang Bo. Xiang Bo had a close friendship with Liu Bang's strategist Zhang Liang, who had once saved his life. Hearing that Xiang Yu was about to attack Liu Bang, Xiang Bo worried for Zhang Liang's safety and secretly rode to him at night, urging him to flee. Zhang Liang, however, insisted on protecting Liu Bang and decided to bring Xiang Bo to meet him. When Liu Bang heard the full story from Zhang Liang, his face turned pale with fear. He repeatedly assured Xiang Bo that he had no ambition to claim kingship, claiming that petty instigators had misled him into actions that angered Xiang Yu. Knowing that war would surely lead to his defeat, Liu Bang sought Xiang Bo's help as a possible way out. He respectfully addressed Xiang Bo as an elder brother and proposed a marriage alliance between their children, his words brimming with reverence for Xiang Bo and praise for Xiang Yu. Seeing Liu Bang's sincerity, Xiang Bo agreed to persuade Xiang Yu to call off the attack, but urged Liu Bang to personally visit Xiang Yu the next day.
The next morning, Liu Bang led a small group of close attendants and soldiers to Hongmen, leaving his troops outside the camp and entering with only his retinue. Xiang Yu, who had not yet mobilized his forces, was surprised to see Liu Bang but could not show anger, so he invited everyone into the tent and ordered servants to bring wine and food. During the banquet, Liu Bang humbly explained that his capture of Xianyang was merely to clear the way for the advancing army, urging Xiang Yu not to heed slanderous rumors. These words filled Xiang Yu with guilt, making him feel he had deeply misunderstood Liu Bang. With his uncle Xiang Bo also speaking well of Liu Bang, Xiang Yu's regret grew, and his intention to kill Liu Bang gradually faded. However, Fan Zeng repeatedly made gestures to remind Xiang Yu of his original plan, but Xiang Yu ignored him. Frustrated, Fan Zeng slipped out of the banquet and intercepted Xiang Yu's cousin, Xiang Zhuang, urging him to enter under the pretense of offering a toast and performing a sword dance, then seize the chance to stab Liu Bang to death. Xiang Zhuang agreed, entered the tent, downed a cup of wine in Liu Bang's direction, and requested Xiang Yu's permission to perform a sword dance for the Duke of Pei. Xiang Yu gladly consented. Xiang Zhuang then drew his sword and began dancing, gradually moving closer to Liu Bang. Xiang Bo immediately recognized Xiang Zhuang's true intent to assassinate Liu Bang, so he also drew his sword and danced opposite Xiang Zhuang, blocking each attempt to strike Liu Bang with his own body.
Liu Bang could see the tension in the air at the banquet and felt a surge of fear in his heart, but he kept up a calm facade, pretending nothing was wrong, though he dared not drink too much. Zhang Liang noticed that Xiang Zhuang's sword thrusts were all aimed at Liu Bang and realized the situation was dire. Seizing a moment, he slipped out of the tent, found Fan Kuai waiting outside, and explained the crisis to him. Fan Kuai immediately charged into the camp, glaring fiercely at Xiang Yu. Xiang Yu thought he was there to start trouble and was about to confront him, but Zhang Liang arrived just in time to explain that this man was merely Liu Bang's charioteer. Xiang Yu let down his guard and rewarded Fan Kuai with a bowl of wine and a half-raw pork shoulder. Fan Kuai, unfazed, sat directly on the ground, used his sword to slice off pieces of meat, and ate them. After finishing, he wiped his mouth, first thanked Xiang Yu for his hospitality, then accused Xiang Yu of being ungrateful, ignoring Pei Gong's goodwill while harboring suspicions against him. Before the western expedition, King Huai of Chu had declared, "Whoever enters Guanzhong first shall be its king." If Pei Gong had claimed the title, why would he have left behind all the gold, silver, and treasures in the storehouses and withdrawn his troops to Ba Shang, waiting for the arrival of the allied armies? If the King of Xiang sought to make trouble for Pei Gong on some pretext, how would that be any different from the brutal rulers of the Qin dynasty?
After hearing Fan Kuai's words, Xiang Yu did not know how to respond.
Shortly after Fan Kuai sat down, Liu Bang took the opportunity of going to the restroom to slip out, with Zhang Liang and Fan Kuai following him out shortly after. Zhang Liang advised Liu Bang to take this chance to return to Bàshàng, leaving him behind to deal with Xiang Yu. Liu Bang had originally brought two gifts but had not yet presented them, so he decided to leave them with Zhang Liang, asking him to offer them to Xiang Yu and Fan Zeng on his behalf. Then, accompanied by Fan Kuai and a few attendants, he rode back to his own camp.
Zhang Liang estimated that the Duke of Pei had not yet traveled far from Bashang, so he leisurely strolled into the camp. When Xiang Yu saw that Liu Bang had not returned, he was startled and asked what was going on. Zhang Liang made an excuse, saying that Liu Bang had drunk too much and feared he might behave improperly in front of King Xiang, so he had left first. He also mentioned that before coming, he had prepared two gifts: a pair of white jade discs for King Xiang and a pair of jade wine cups for Yafu (Xiang Yu's respectful title for Fan Zeng).
Upon hearing Zhang Liang's words, Fan Zeng was so enraged that he drew his sword and slashed at the jade dou, which shattered into pieces on the ground. Thinking of Xiang Yu's soft-heartedness, Fan Zeng lamented inwardly: one day, they would surely be utterly wiped out by Liu Bang.
Relying on his own composure and the help of others, Liu Bang narrowly escaped death at the hands of Xiang Yu, which further strengthened his resolve to eliminate Xiang Yu and seize control of the realm. Shortly after, Xiang Yu occupied Xianyang, but unlike Liu Bang, who had pacified the people, he killed the Qin emperor Ziying along with nearly all the nobles, officials, and ministers. The Chu army plundered the palaces of treasures and beautiful women, and Xiang Yu even ordered the Qin palaces set ablaze, with the fire raging for days and nights. He then honored King Huai of Chu as the Righteous Emperor and enfeoffed the various generals who had participated in the anti-Qin campaign as feudal lords, including Liu Bang as the King of Han and Ying Bu as the King of Jiujiang. Each lord was assigned a sphere of influence, totaling eighteen feudal lords. Xiang Yu declared himself the Hegemon-King of Western Chu, established his capital at Pengcheng, and became the supreme leader among the lords.