Meng Da
When Meng Da learned that Liu Bei was going to launch a campaign against Sun Quan, he became concerned that he would be punished for not sending reinforcements to Guan Yu earlier, so he defected to Wei. At the same time, Zhao Yun, Qin Mi and others reminded Liu Bei that he should focus his attack on Cao Pi instead of Sun Quan, but Liu Bei rejected their advice. Seeing that Liu Bei did not prepare strong defences against Wei, Meng Da suggested a plan to Cao Pi to attack Fangling, Shangyong and Xicheng commanderies. Liu Bei's adopted son, Liu Feng, fought a desperate battle against the invaders, but he was betrayed by his subordinates and defeated. Upon his return to Chengdu, Liu Bei was furious with Liu Feng's loss and his refusal to send reinforcement to Guan Yu in 219. Upon Zhuge Liang's suggestion, Liu Bei had Liu Feng commit suicide and wept after he died.