After Guan Yu slew Yan Liang and lifted the siege on Boma, Cao Cao knew that he would leave soon so he gave Guan Yu greater rewards. Guan Yu sealed up all the gifts he received from Cao Cao, wrote a farewell letter, and headed towards Yuan Shao's territory to find Liu Bei. Cao Cao's subordinates wanted to pursue Guan Yu, but Cao Cao stopped them and said, "He's just doing his duty to his lord. There's no need to pursue him."