Yan Liang
Before the Battle of Guandu between Yuan Shao and Cao Cao, both sides have already engaged in two skirmishes: the Battle of Boma and Battle of Yan Ford. Yuan Shao sends his generals Yan Liang and Wen Chou to attack Cao Cao's fortress at Boma (白馬; near present-day Hua County, Henan). During the battle, some of Cao Cao's best warriors, including Xu Huang and Zhang Liao, go forth to take up Yan Liang's challenge but are defeated by him. Cao Cao reluctantly allows Guan Yu to fight Yan Liang and Guan emerges victorious. Wen Chou later comes to avenge Yan Liang but ends up being slain by Guan Yu in a rout. The siege on Boma is lifted as a result.