On the eve of Red Cliffs, in the novel, Cao Cao sends Jiang Gan to talk Zhou Yu into surrender. Zhou Yu feasts him, pretends to be drunk, and lets him see a forged letter in which Cai Mao and Zhang Yun promise to defect. Jiang Gan steals it. Cao Cao, in anger, kills the two officers who understood naval war, and only afterward sees the trick.
Pei Songzhi quotes the Jiangbiao zhuan for the visit itself. Zhou Yu shows Jiang Gan the camp and says they are men of the same region and may talk of other things, but this campaign is not a matter for persuasion. They drink. Jiang Gan has nothing to say. He returns and tells Cao Cao that Zhou Yu cannot be moved by words. There is no letter, no false defection of Cai Mao and Zhang Yun, and no execution that follows.
Jiang Gan has a historical shadow. The theft does not. The stratagem is marked as romance. It serves the novel’s Zhou Yu: the drinking, the performance, the calculation against Cao Cao. The decision to use fire still belongs to Huang Gai’s counsel with Zhou Yu, not to a stolen page.