Is “Repeatedly defeated by Zhuge Liang and eventually died of anger from a letter” true?
novel invention
The Records of the Three Kingdoms, Book of Wei, Biography of Cao Zhen records that Cao Zhen repelled Shu forces multiple times and achieved many military exploits; in the novel, his death from anger after receiving a letter from Zhuge Liang is pure fiction, as Cao Zhen actually died of illness in Luoyang.
Cao Zhen
In official history, he was a Grand Marshal of Wei who skillfully commanded troops and repeatedly defeated Shu forces, but in the novel he is reduced to a foil who is infuriated to death.