Hefei was Cao Cao’s strongpoint in Huainan. It covered Yu and Xu provinces, and it was the first hard place Sun Quan met when he marched north from Jianye. In 215, leaving for the Zhang Lu campaign, Cao Cao gave Xue Ti a sealed instruction: if Sun Quan came, Zhang Liao and Li Dian should attack and Yue Jin should hold the city. Sun Quan arrived with an army numbered at a hundred thousand. The defenders were about seven thousand.
Zhang Liao recruited a shock force and struck Sun Quan’s camp. Sun Quan fell back north of Xiaoyao Ford. The Wu army returned, and Zhang Liao fought again. Sun Quan crossed the ford on horseback and nearly was captured. The action is remembered as Xiaoyao Ford and, more loosely, as the battle of Hefei. Cao Cao was on the Hanzhong front, not on the wall.
Sun Quan tried the Huainan line again, including the later New City of Hefei, and did not tear it open. The novel heightens Zhang Liao’s courage and Sun Quan’s embarrassment. The frame matches the biographies of Zhang Liao and Sun Quan. It shows that Wu’s northern edge stayed on the Huai. One victory at Red Cliffs did not open the central plains.