by Yuan Shu. During this time, he left Zhang Fei behind to guard Xiapi, the capital of Xu Province. Zhang Fei wanted to kill Cao Bao, a former officer under Tao Qian, for reasons unknown. Cao Bao fled back to his own camp and set up defences while sending a messenger to request aid from Lü Bu, another warlord who was taking shelter under Liu Bei at the time. Lü Bu led his forces to attack Xiapi and succeeded in seizing control of Xiapi. Zhang Fei fled after losing Xiapi to Lü Bu. Liu Bei returned to Xu Province, which was now under Lü Bu's control, and reluctantly accepted Lü Bu's offer to move to Xiaopei while Lü Bu remained in Xiapi. Tensions between Liu Bei and Lü Bu increased until the point of conflict. Liu Bei sought help from Cao Cao, a warlord who controlled the Han central government. Cao Cao and Liu Bei combined forces and defeated Lü Bu at the Battle of Xiapi in 198, after which they returned to the imperial capital Xu together. In Xu, Zhang Fei was appointed as a General of the Household (). Roaming the land with Liu Bei In 199, Liu Bei pretended to volunteer to lead an army to attack Yuan Shu, and used that opportunity to leave Xu and escape from Cao Cao's watch. He headed to Xu Province, killed Che Zhou, the provincial governor appointed by Cao Cao, and seized control of Xiapi again. The following year, Cao Cao personally led his forces to attack Liu Bei, defeated him, and took back control of Xu Province. After his defeat, Liu Bei fled to Ji Province, where he took refuge under Cao Cao's rival, Yuan Shao. Liu Bei later left Yuan Shao by pretending to help Yuan Shao gain support from local rebels in Runan in his war against Cao Cao. He eventually found shelter under Liu Biao, the Governor of Jing Province. Liu Biao put him in charge of Xinye County on the northern border of Jing Province. It is not known whether Zhang Fei followed Liu Bei to join Yuan Shao after Liu Bei's defeat in Xu Province, or whether he, like Guan Yu, was separated from Liu Bei during that period of time. Red Cliffs campaign Battle of Changban In 208, following Liu Biao's death, Cao Cao launched a military campaign aimed at wiping out opposing