Yan Liang
As Yuan Shao's forces at Liyang was numerically superior to Cao Cao's forces, Cao Cao's strategist Xun You suggested seeking to split Yuan Shao's forces using a diversionary tactic and take out the less capable Yan Liang. Cao Cao adhered to this plan and marched towards Yan Ford as if trying to cross the river to attack Yuan Shao's rear. Reacting to this apparent threat, Yuan Shao split off his men in Liyang and came west along the northern bank of the river, thus falling for the feint. Rapidly, Cao Cao led light troops east toward Boma, and engaged a startled Yan Liang some ten "li" west of the outpost. Cao Cao sent Zhang Liao and Guan Yu (now supporting Cao Cao after Liu Bei was defeated in Xu Province) to lead the vanguard. Noticing Yan Liang's standard from afar, Guan Yu charged through thousands of enemy troops, virtually unopposed, toward Yan Liang, killed him with a stroke, decapitated him, and returned with Yan's head. Thus the siege of Boma was broken.