Xun You
Cao Cao's troops began to become tired and weary after failing to capture Xiapi despite besieging it for a long time. Cao Cao had the intention of withdrawing, but his strategists Xun You and Guo Jia thought that Lü Bu's army was already low on morale after having suffered so many defeats, so they advised Cao Cao to press on with the siege. Cao Cao then ordered his soldiers to direct the waters of the Yi and Si Rivers to flood Xiapi. The beleaguered Lü Bu prepared to surrender after Xiapi was flooded for over a month, but Chen Gong stopped him.