“Sima Zhao is as crafty as Cao Cao. If he slew all Wang Jing's family, would he have left a nephew and sent that nephew to the pass beyond his own reach with soldiers? You saw this, as did I.”
So Jiang Wei did not go out by the Xie Valley, but he set an ambush there ready for any move of Wang Guan. And indeed, within ten days, the ambush caught a man with a letter from Wang Guan to Deng Ai telling him what had come about. From the letter and the bearer thereof, Jiang Wei learned that Wang Guan
would divert a convoy of grain to the Wei camps on the twentieth and Deng Ai was to send troops to Yunshan Valley to help.
Jiang Wei beheaded the courier. Then he sent another letter to Deng Ai by a man dressed as a Wei soldier, the date being altered to the fifteenth instead of the twentieth.
As a preparation, Jiang Wei ordered many wagons to be emptied of their grain and laden with inflammables, covered with green cloth. The two thousand Wei soldiers were ordered to show flags belonging to the Shu transport corps. Then Jiang Wei and Xiahou Ba went into the valleys in ambush, while Jiang Shu was ordered to march to the Xie Valley, and Liao Hua and Zhang Yi were sent to capture Qishan.
The letter, apparently from Wang Guan, was sufficient for Deng Ai, and he wrote back to say it was agreed. So on the fifteenth day, Deng Ai led out fifty thousand veteran troops and moved in sight near Yunshan Valley. And the scouts saw endless carts of grain and fodder in the distance zigzagging through the mountains. When Deng Ai got closer, he distinguished the uniforms of Wei.
His staff urged him, saying, “It is getting dark; O General, hurry to help Wang Guan escort the convoy out of the valley.”
“The mountains ahead are hazardous,” said the general. “If by any chance an ambush has been laid, we could hardly escape. We will wait here.”
But just then two horsemen came up at a gallop and said, “Just as General Wang Guan was crossing the frontier with the convoy, he was pursued, and reinforcements are urgently needed.”
Deng Ai, realizing the importance of the request, gave orders to press onward. It was the first watch, and a full moon was shining as bright as day. Shouting was heard behind the hills, and he could only conclude it was the noise of the battle in which Wang Guan was engaged.
So Deng Ai dashed over the hills. But suddenly a body of troops came out from the shelter of a grove of trees, and at their head rode the Shu leader, Fu Qian.
“Deng Ai, you are stupid! You have just fallen into the trap set for you by our general. Dismount and prepare for death!”
Deng Ai halted and turned to flee. Then the wagons burst into flame. That flame was a signal, and down came the army of Shu. He heard shouts all round him, “A thousand ounces of gold for anyone who captures Deng Ai, and a lordship of ten thousand households as well!”
Terrified, Deng Ai dropped his arms, threw aside his armor, slipped from his steed, mingled with the footmen, and with them scrambled up the hills. The generals of Shu only looked for him among the mounted leaders, never guessing that he had got away among the common soldiers. So he was not captured.
Jiang Wei gathered in his victorious army and went to meet Wang Guan and his convoy.
Having made all arrangements, as he thought, complete, Wang Guan was patiently awaiting the development of his scheme, when a trusted subordinate came and told him that the ruse had been discovered and Deng Ai had already suffered defeat. Wang Guan sent out some scouts, and the report was confirmed, with the addition that the Shu armies were coming against him. Moreover, clouds of dust were rising. There was no way of escape, so Wang Guan ordered his troops to set fire to the convoy, and soon huge flames were rising high into the air.
“The case is desperate,” cried Wang Guan. “It is a fight to the death!”
He led his force westward, but the army of Shu came in pursuit. Jiang Wei thought Wang Guan would try at all costs to get back to his own side, but instead, Wang Guan went on toward Hanzhong; and as his troops were too few to risk a battle, Wang Guan ordered them to burn and destroy all military stations and even the Plank Trail as he went. Fearing the loss of Hanzhong, Jiang Wei made all haste along the by-roads after Wang Guan. Surrounded on all sides, Wang Guan jumped into the Black Dragon River and so died. Those of his soldiers who survived were slain by Jiang Wei.
Though a victory had been won and Wang Guan killed, it was costly. Many wagons and much grain had been lost, and the Plank Trail had been destroyed. Jiang Wei led his army into Hanzhong.
