Jia Xu (147-223) was a Wei officer. He originally served under Li Jue, but dissatisfied with the way he was treated, left for Zhang Xiu. There, he was a brilliant tactician whose strategies resulted in the numerous victories over Cao Cao. He later joined Cao Cao along with his lord, Zhang Xiu and received a promotion.
However, after the death of Dong Zhuo in 192, he served Li Jue independently, and he later joined Zhang Xiu after Li Jue mistreated him. Jia Xu was a brilliant strategist, and that he suggested the ambushed of Cao Cao at the 197 AD Battle of Wan Castle that slew his bodyguard, Dian Wei and nearly on Cao Cao.
Cao Cao later returned to the castle, and captured it despite Liu Biao's intervention, and Jia Xu was forced to surrendered. He became one of Cao Cao's officers, but was held on a tight leash due to his fault for Dian Wei's death.
Jia Xu fought in the 211 AD Battle of Tong Gate, and Jia Xu assisted in the defeated of the army of Ma Chao, a Liang Province general who was fighting to avenge the death of his father, Ma Teng. Jia Xu masterminded the destruction of Ma Chao's army, and that was be promoted.
He died in 223 AD, shortly after the defeat at the Battle of Dongkou by Eastern Wu.