In retaliation, an expeditionary force under Duke Wen marched south in the spring of the following year and occupied the States of Wey and Cao, both satellites of Chu.
[2] As promised by Duke Wen to King Cheng during his exile in Chu, the Jin army retired "three days march" (退避三舍) (45 km) before camping on the plain of Chengpu on the border of Wey and Cao, awaiting a decisive battle.
The Jin force was expanded before the expedition from two armies into three: the upper, the central and the lower; these three were then regrouped into wings before the battle: the upper army at the right wing under commander Hu Mao and vice-commander Hu Yan, lower at left under Luan Zhi and vice Xu Chen, central remained at center under Xian Zhen and vice Xi Zhen.
A contingent of chariots under Luan Zhi swept in front and dragged tree branches to raise a dust cloud and thereby obscure the movements of Hu Mao's men who were circling and reforming.
Seeing both his wings enveloped, Ziyu ordered a general retreat, which turned into rout when it was discovered that the Chu camp and train in the rear had been captured during the battle by the Qi and Qin contingents, which had been sent to occupy it via a flanking march.
Nevertheless, the location of the battle remains obscure: two inconclusive possibilities are the vicinity of Chenliu, Henan and the southwest area of Juancheng County, Shandong.
A multi-state conference at Jiantu in 631 BC headed by Duke Wen confirmed their support for the Zhou royal family and swore a covenant of alliance.