In AD 184 (the first year of Zhong Ping), Liu Bei, a relative of the Han clan, organized volunteers to fight against the Yellow Scarf Army in Zhuoxian. Guan Yu and Zhang Fei are among them. After Liu Bei was transferred to many official posts, he defected to his former classmate Gongsun Zan, and was named the Plain Country. Guan Yu and Zhang Fei were appointed as other horses and enfeoffed different departments. Three people are brothers and often sleep in the same bed. After Liu Bei was seated, Guan and Zhang took good care of him.
194 (the first year of Xingping), Cao Cao was angry at Tao Qian because Cao Song was killed, so he sent troops to attack Xuzhou. Tao Qian asked Liu Bei for help, and Liu Bei and Guan Yu led thousands of people to come to the rescue. Cao Caobing retired, Tao Qianli Liu Bei was the secretariat of Yuzhou, and Guan Yu and Liu Bei stationed troops for Xiao Pei. So, under the repeated compromise of Tao Qian and others, Liu Bei led Xuzhou Pastoral.
In A.D. 196 (the first year of Jian 'an), Liu Bei was attacked by Yuan Shu and Lu Bu and lost Xuzhou. Guan Yu followed Liu Bei to Cao Cao. Later, when hunting with Cao Tian, Guan Yu advised Liu Bei to kill Cao Cao, but Liu Bei thought that Cao Cao at that time was trying to help the Han Dynasty, and felt it was a pity to kill him, so he refused.
198 (the third year of Jian 'an), Liu Bei and Cao Cao jointly captured Lu Bu and captured Xuzhou. Guan Yu and Liu Bei followed Cao Cao's troops back to Xuchang, and Cao Cao appointed Che Zhou as the secretariat of Xuzhou. After Yuan Shu went north to Yuan Shao, Liu Bei was ordered by Cao Cao to intercept Yuan Shu in Xuzhou. Liu Bei took the opportunity to attack and kill Che Zhou, ordered Guan Yu to keep Pi, led Xuzhou, and Liu Bei returned to Xiaopei.