Xun Yu
Cao Cao had shifted his focus away from the Yuan clan after his victorious Guandu campaign, but eventually returned to the frontline fortifications in Guandu in the spring of 202. His advisor Xun Yu had previously warned Cao Cao to not turn his back on his newly defeated enemy, lest the remnants regroup and strike from behind. Four months after Yuan Shao's death, Cao Cao led his army across the Yellow River to attack the remnants at Liyang.