Shen Pei
In 200 CE, when the Battle of Guandu broke out between Yuan Shao and his rival Cao Cao, Yuan Shao put Shen Pei in charge of overall coordination and mobilisation of troops. During this time, Shen Pei caught the family members of Xu You, another of Yuan Shao's advisers, committing crimes so he had them arrested. He then reported the incident to Yuan Shao. Xu You, fearing that he had fallen out of Yuan Shao's favour, escaped from Yuan Shao's camp and defected to Cao Cao's side. Xu You then suggested to Cao Cao to attack Yuan Shao's supply depot, resulting in the tide turning against Yuan Shao and consequently leading to Cao Cao's eventual victory. Two of Shen Pei's sons were captured by Cao Cao's forces during the battle. When rumours started spreading that Shen Pei was planning to betray Yuan Shao, Pang Ji, another of Yuan Shao's advisers, spoke up for Shen Pei. As a result, Shen Pei and Pang Ji became good friends.