樊城の戦い
Sima Yi also warned Cao Cao about Hu Xiu () and Fu Fang (), who respectively served as the Inspector of Jing Province and the Administrator of Nanxiang Commandery (南鄉郡; in Jing Province) at the time. He said that Hu Xiu was violent while Fu Fang was arrogant, so they should not be entrusted with the important responsibility of guarding the border at Jing Province. Cao Cao ignored him. In 219, during the Battle of Fancheng, while Cao Cao's general Cao Ren was besieged by Liu Bei's general Guan Yu in Fancheng, Cao Cao ordered Yu Jin to lead reinforcements to lift the siege on Fancheng. However, the reinforcements were destroyed in a flood and Yu Jin surrendered to Guan Yu. As Sima Yi foresaw, Hu Xiu and Fu Fang defected to Guan Yu, placing Cao Ren in an even more perilous situation.