Yuan Tan
Cao Cao's advisor Guo Jia then suggested that the Yuan brothers would fight between themselves in the absence of an external enemy. Cao Cao took the counsel and withdrew his troops to attack Liu Biao in Jing Province (present-day Hubei and Hunan). Meanwhile, Yuan Tan and Yuan Shang indeed battled each other. After suffering initial defeats, Yuan Tan retreated to Pingyuan and sent out an emissary seeking to ally with Cao Cao. Cao Cao agreed, but his actual intention of allying with Yuan Tan was to make it easier to defeat Yuan Shang and Yuan Xi, and with them gone, he would then eliminate Yuan Tan easily. On the other hand, however, Yuan Tan was trying to make use of the alliance to strengthen his position. He contacted two of his father’s former generals, who had surrendered to Cao Cao, and gave them seals of authority, in hope they would defect to him at the right time after Yuan Shang was taken care of. But his plan was sensed by Cao Cao, who even promised to marry a daughter to Yuan Tan in order to let his guard down.