Cao Cao personally led a million-strong army, intending to cross the Yangtze River and take Soochow directly. Zhou Yu, commander-in-chief of Soochow, also led troops across the river to confront Cao Jun. Jiang Gan, Cao Cao's counselor, recommended himself to Cao Cao because he studied with Zhou Yu since he was a child. He wanted to cross the river and surrender to Zhou Yu in Soochow. So, Zhou Yu made a plan to let Jiang Gan steal the fake surrender book written by Cao Cao's commander-in-chief Cai Mao and Zhang Yun to Zhou Yu. Jiang Gan presented books to Cao Cao, who ordered him to behead Cai Mao and Zhang Yun.
2. The background of Jiang Gan stealing books:
This story happened on the eve of the Red Cliff War in the Three Kingdoms. Cao Cao personally led a million-strong army, stationed on the north bank of the Yangtze River, crossed the Yangtze River and took Soochow directly. Zhou Yu, commander-in-chief of Wu Dong, also led troops across the river to confront Cao Jun. The two sides are at daggers drawn, preparing for a big battle.
3. The cause of "Jiang Gan stealing books":
Jiang Gan, Zi Ziyi, was Cao Cao's counselor. As he was a classmate of Zhou Yu's since childhood, he volunteered to ask Cao Cao to cross the river to Wu Dong as a lobbyist to persuade Zhou Yu not to take part in the war. Cao Cao heard that he was overjoyed and personally bought wine to see Jiang Gan off.