195 (the second year of Xingping), Cao Cao successfully defeated Lu Bu in the battle of Yanzhou, and Lu Bu had to lead his troops to the new Xuzhou to shepherd Liu Bei. Later, Cao Cao welcomed Emperor Xiandi of Han Dynasty to move to Xu County, and began the era of "serving Tianzi to make him not a minister".

In A.D. 196 (the first year of Jian 'an), Liu Bei and Yuan Shu were at loggerheads in the war. Lu Bu attacked Xuzhou and took over Xuzhou as a shepherd. Liu Bei was forced to take refuge in Lu Bu and live in Xiaopei temporarily. But not long after, Lu Bu was uneasy because Liu Bei gathered more and more soldiers, and led the troops to attack Liu Bei. Liu Bei was defeated and had to take refuge in Cao Cao. Cao Cao provided him with food and continued to be stationed in Xiaopei.

A.D. 197 (the second year of Jian 'an), when Yuan Shao had annexed Heshuo and controlled Hebei, Qinghai and Hebei provinces, he was in full swing. Cao Cao was defeated by Zhang Xiu in Wancheng. Yuan Shao was arrogant in his letter to Cao Cao, and Cao Cao was furious. He was worried that Yuan Shao's strength would annex him, wanted to crusade, and felt that his strength was lost. So Guo Jia and Cao Cao analyzed Yuan and Cao Cao's ten wins and ten losses (Yu Xun's version is "four wins and four losses"), and urged Cao Cao to take advantage of Yuan Shao's sneak attack on Gongsun Zan to destroy Lu Bu first, so as to prevent Lu Bu and Yuan Shao from fighting Yuan Shao once. Cao Cao then prepared to attack Lu Bu.