Han Xin then proceeded with his master plan: "Ambush from Ten Sides" (). Han Xin first fought Xiang Yu face to face, and then retreated. Xiang Yu immediately gave chase, but soon found himself trapped among the numerous Han army. Everywhere Xiang Yu led his forces, more ambushes and traps awaited them. With the repeated ambushes and encirclements, the Han troops began to elongate Xiang Yu's columns and disrupt their formation, allowing their decimation piecemeal. This not only caused heavy casualties for Chu, but also crushed the Chu army's morale, since escaping alive seemed impossible. By December 202 BC, the Chu troops were trapped without supply in the canyon.