Meng Da

Meng Da was a general who served under Liu Zhang, Liu Bei, Cao Pi, and Cao Rui. Like fellow conspirators Zhang Song and Fa Zheng, who also sought to hand Shu to a more capable ruler, Meng Da pledged his allegiance to Liu Bei upon his entry into Shu.

Ascent to Governor
When Liu Bei was invited to Shu by Liu Zhang, Meng Da and Fa Zheng were dispatched with 2000 soldiers each to act as an escort. Liu Bei ordered Meng Da to lead these troops to Jiangling. Upon the pacification of Shu, he was given a post as Governor of a capital city.

Defection
In 219 AD, Meng Da was sent north to capture the city of Fangling. Kuai Qi, Governor of Fangling, was defeated and killed. Meng Da advanced to take the city of Shangyong, with Liu Feng leading reinforcements from Mianshui to join him. Shen Dan, governor of Shangyong, surrendered.

Later in the same year, Guan Yu was engaged in battle against forces from both Wu and Wei. A request for military aid was sent to Liu Feng and Meng Da in Yishan county. They refused the request on the basis that Yishan was beginning to be surrounded, and hence troops could not be sent.

When Guan Yu was ultimately defeated and Liu Bei heard of his death, he began to hate Liu Feng and Meng Da. At this point in time, the two men had also had a dispute. Meng Da, fearing punishment and bearing hatred for Liu Feng, defected to Wei along with his subordinates (amongst them the former Wei officers Shen Dan and Shen Yi). Afterwards, he wrote a letter to Liu Feng rebuking him and urging him to also surrender to Wei. This was not heeded, and Liu Feng was subsequently executed for failing to assist Guan Yu and stop Meng Da from defecting.

Death
In 227, Zhuge Liang launched a campaign into Wei. Meng Da, who had been treated kindly by the late Emperor Cao Pi but was less favorably received by Cao Rui, was persuaded to return to the service of Shu, and moreover assist in the campaign by striking at Luoyang. However, Meng Da's failure to take necessary precautions and the betrayal of Shen Dan, Shen Yi and others led to his eventual defeat and death at the hands of Sima Yi.