Meng Da
In 219, Liu Bei ordered his general Meng Da to lead an army from Zigui County to attack Fangling County (房陵縣; present-day Fang County, Hubei), which was defended by Kuai Qi (). Meng Da defeated Kuai Qi in battle, conquered Fangling County, and then proceeded to attack Shangyong Commandery (上庸郡; around present-day Zhushan County, Hubei). Liu Bei was worried that Meng Da could not manage alone, so he sent Liu Feng to lead a force from Hanzhong Commandery and sail down the Mian River () to rendezvous with Meng Da at Shangyong. Shen Dan (), the Administrator of Shangyong, surrendered to Meng Da and Liu Feng. For his achievement, Liu Feng was promoted to Vice-General (). Later that year, when Liu Bei's general Guan Yu led an army from Jing Province to attack an enemy garrison at Fan (樊; or Fancheng, present-day Fancheng District, Xiangyang, Hubei), he repeatedly asked Meng Da and Liu Feng to lead reinforcements from Shangyong to support him but they refused, claiming that the situation in Shangyong was not stable yet. Eventually, Guan Yu not only failed to conquer Fan, but also lost his lord's territories in Jing Province in a stealth invasion by Liu Bei's ally Sun Quan, who had turned against Liu. Guan Yu was captured and executed by Sun Quan's forces. Liu Bei resented Liu Feng and Meng Da for not aiding Guan Yu. At the time, Liu Feng had a quarrel with Meng Da. Meng Da became afraid when he heard of Liu Bei's anger towards him and was also worried about his dispute with Liu Feng, so he brought along his followers and defected to the state of Cao Wei, which was established by Liu Bei's rival Cao Pi.