Zhang Song
After the Battle of Red Cliffs, Sun Quan invited Liu Bei to take Yi Province with him, but the latter strongly rebutted the former, saying: "if you're going to conquer the land of Shu, I will loosen my hair and become a hermit in the deep hills. Earth under Heaven can hear my promise, and I'll live up to my words!" Believing Liu Bei, Sun Quan aborted his plan; however, Liu Bei was actually trying to take Yi Province for himself and negotiated Yiling County and Nan Commandery from Sun Quan. In 211, Liu Zhang, the Governor of Yi Province, heard that Cao Cao was planning to attack Zhang Lu in Hanzhong Commandery. As Hanzhong Commandery was a strategic location and the "gateway" into Yi Province, Liu Zhang sent Fa Zheng to form an alliance with Liu Bei after Zhang Song convinced him to do so. Liu Bei then led his men to Yi Province under the pretence of helping Liu Zhang conquer Hanzhong Commandery.