Fa Zheng
In 217, Liu Bei's adviser Fa Zheng analysed the reason Cao Cao left Xiahou Yuan to guard Hanzhong Commandery: Hanzhong was still unstable (partly due to the massive relocation enforced by Cao Cao). Fa Zheng also believed Xiahou Yuan and Zhang He were not good commanders, so the pair could not defend Hanzhong Commandery. Hence, Fa Zheng urged Liu Bei to attack Hanzhong Commandery, stating three benefits if the commandery could be taken: ideally it could serve as a base of operations to attack Cao Cao and revive the Han dynasty; if that were not possible one could still attack Yong and Liang provinces from it (Hanzhong Commandery granted access to the two provinces) and expand his territory; and finally Hanzhong Commandery had long-lasting strategical impact on the survival of Liu Bei's regime. Liu Bei agreed with Fa Zheng's analysis and ordered him to plan for the upcoming campaign.