The siege of Chenggao (204 BC) was the second occasion during the same year in which Liu Bang, the eventual founder of the Han Dynasty, was forced to flee from a besieged city with a handful of supporters (Chu-Han Contention).
Earlier in 204 Liu Bang had been forced to flee from Xingyang, close to Chenggao, when the city was besieged by Xiang Yu. Liu was forced to retire west to raise a new army. He then moved to Yuan, to the south of Chenggao and Xingyang. As his advisors had hoped Xiang Yu also moved south, relieving some of the pressure on Xingyang. Liu Bang had constructed strong fortifications at Yuan, and refused to leave them to fight an open battle. Xiang Yu was then forced to move east to restore the situation after another of his armies was defeated at Hsia-p’ei.
This allowed Liu Bang to move back to Chenggao, where he defeated an army led by one of Xiang Yu’s generals, but was unable to lift the siege of Xingyang. Xiang soon returned from the east, and ended the siege by storming the city. Liu Bang’s commanders within the city were captured and executed.
When this happened Liu Bang was still close by at Chenggao. Xiang Yu moved out to attack him, defeating or driving away most of the Han army and leaving Liu Bang trapped in Chenggao.
His escape from Xingyang had involved a certain amount of deception. His escape from Chenggao was rather more straightforward. With a single supporter, Xiahou Ying, Liu Bang escaped through the northern gate of the city (the Jade Gate).
After escaping from Chenggao Liu Bang crossed the Yellow River, and joined one of his other armies, commanded by Han Xan. Liu Bang’s control over this trusted subordinate may not have been as secure as is often stated. At first Liu Bang had trouble getting into the army camp, eventually gaining access by claiming to be a messenger from himself. He then went to his subordinate’s tents and took their seals without waking them, only revealing his presence once he had secure control of his army. Han Xan was then ordered to take part of the army and conquer Qi, a campaign that led to the battle of the Wei River.
Chenggao itself soon fell to Xiang Yu’s men, and wasn’t reoccupied by Liu Bang until after the battle of the Si River early in 203 BC.