The Battle of Chengpu is the earliest war case recorded in detail in the history of China, and it is also a model of luring the enemy into depth tactics. It is said that this is Xian Zhen's plan. In 632 BC, on the fourth day of April, the Chu army and the Jin army fought in Chengpu (now southwest of Juancheng, Shandong Province). When Jin Wengong exiled Chu, he kept his promise of "staying away from three houses", which made the Jin army lose ground and avoided the edge of the Chu army. Yu Zi ignored the warning of the King of Chu and led an aggressive army, which was annihilated by the Jin army. The Chu army was defeated.