Zhang Song
In 211, Liu Zhang, the Governor of Yi Province (covering present-day Sichuan and Chongqing), heard that Cao Cao planned to attack the warlord Zhang Lu in Hanzhong Commandery. As Hanzhong Commandery was a strategic location and the northern "gateway" into Yi Province, Liu Zhang was afraid. At this time, the mounted escort Zhang Song told him: "Cao Cao's armies are strong and without a match in the empire. If he was able to use Zhang Lu's grain stores and launch an invasion of Yi province, who could stop him." Liu Zhang answered that he was worried but without a plan. Zhang Song answered: "Liu Bei is of the same clan as you and he is an unstoppable rival of Cao Cao. He commands troops with talent. If we used him to conquer Zhang Lu, Zhang Lu would surely be defeated. With Zhang Lu vanquished, Yi province would be safe and even if Cao Cao were to come, he would be defeated."