Xun You
Shortly after, Yuan Shao's advisor Xu You, who had harboured dissatisfaction against Yuan Shao for not following his plan and having his wife arrested by Shen Pei, defected over to Cao Cao. He understood Cao Cao's shortage of supplies and alerted Cao Cao to Yuan Shao's exploitable weakness at Wuchao. Cao Cao's generals were suspicious of this piece of intelligence, but his advisors Xun You and Jia Xu urged Cao Cao to put Xu You's plan to action. Thus at night, Cao Cao led 5,000 infantry and cavalry to attack Wuchao after leaving Cao Hong and Xun You in charge of his main camp at Guandu. Cao Cao's army disguised itself as a reinforcement unit from Yuan Shao and attacked Wuchao. Chunyu Qiong's initial defences were overrun, and he retreated to hold his forts, which Cao Cao attacked and set on fire.