In 627 BC, Duke Mu planned a secret attack on the State of Zheng, but the Qin army retreated after being tricked into believing that Zheng was already prepared for Qin's invasion. Duke Wen had died and his successor, Duke Xiang of Jin, ordered his troops to lay an ambush for the retreating Qin army. The Qin forces were defeated at the Battle of Xiao (near present-day Luoning County, Henan) and suffered heavy casualties, and all three of its generals were captured but later released. Three years later, Qin attacked Jin for revenge and scored a major victory. Duke Mu refused to advance further east after holding a posthumous funeral service for those killed in action at the Battle of Xiao, and went back to focus on the traditional policy of expanding Qin's borders in the west. Duke Mu's achievements in the western campaigns and his handling of foreign relations with Jin earned him a position among the Five Hegemons of the Spring and Autumn period.