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During the Spring and Autumn period, the states of Qin and Jin launched a joint attack on Zheng. Zheng sent its minister, Zhuzhiwu, to forge a separate alliance with Qin.
According to the agreement, Qin's forces, led by Qizi, Fengsun, and Yangsun, were stationed in Zheng, and Qin's main army withdrew.
Later, Qizi secretly sent a messenger back to Duke Mu of Qin, urging him to deploy troops again. When the Qin army mounted a large-scale invasion,
a Zheng merchant named Xiangao pretended to be an envoy and warned Qin, implying Zheng was well-prepared. Realizing their surprise attack was compromised, the Qin army was compelled to change its target and attacked the state of Hua instead.