沛県
Cao Shen was from Pei County in present-day Jiangsu and he served as a prison warden in his early days. He was a close friend of Liu Bang. Once, Liu Bang was tasked with escorting some convicts to Mount Li to become labourers, but some prisoners escaped and Liu was forced to become a fugitive. He sought refuge with his followers on Mount Mangdang (in present-day Yongcheng, Henan) and maintained secret contact with Cao Shen and Xiao He. In 209 BC, after the Dazexiang Uprising broke out, the magistrate of Pei County considered rebelling against the Qin dynasty as well, so he heeded Cao Shen and Xiao He's advice to invite Liu Bang back to support him. However, the magistrate changed his mind later and denied Liu Bang entry into the city. He was worried that Xiao He and Cao Shen might open the city gates for Liu Bang so he planned to have them killed, but Xiao and Cao managed to escape and join Liu. The townsfolk rebelled against the magistrate and killed him and allowed Liu Bang and his men to enter. Liu Bang built up his rebel army in Pei County and Cao Shen served as one of his advisors.