官渡之战
In 200 CE, Yuan Shao lost the Battle of Guandu against his rival, Cao Cao, who controlled the Han central government and the figurehead Emperor Xian. After Yuan Shao's defeat, only the troops under Gao Gan's command in Bing Province, numbering about 50,000, were the most organised and highest in morale among all of Yuan Shao's forces.