Is “Refused to rescue Guan Yu, leading to Guan Yu's defeat and death” true?
attested in history
According to Records of the Three Kingdoms, Book of Shu, Biography of Liu Feng, when Guan Yu sent for help, Meng Da and Liu Feng refused to send troops because the mountain commandery had recently submitted. Later, fearing punishment, they defected to Wei.
Meng Da
A general who was seen as capricious in official histories, defecting to Wei and then planning to return to Shu Han.