In 219, when Cao Cao was on a journey back from Mobei (摩陂; southeast of present-day Jia County, Henan), he treated Xiahou Dun like a close aide by letting Xiahou ride in the same carriage as him and allowing Xiahou to enter his private quarters. At the time, Emperor Xian had made Cao Cao a vassal king under the title "King of Wei" () and granted him permission to set up an independent vassal kingdom, which was still nominally under Han imperial control. While many of Cao Cao's subordinates had been appointed to positions in his vassal kingdom, Xiahou Dun still held appointments under the Han central government. Xiahou Dun requested to serve in Cao Cao's vassal kingdom to show his loyalty, but Cao Cao told him, "I heard that the best rulers learn from their subjects while the second best befriend their subjects. Officials are noble men of virtue. Why lower yourself to serve such a small kingdom like Wei?" Xiahou Dun insisted, so Cao Cao appointed him as General of the Vanguard (). Xiahou Dun then led his men to Shouchun () and later garrisoned at Zhaoling ().