Shen Pei said, “I recognize one of Guo Tu's stratagems and if you go, my lord, you will be the victim of their plot. Rather strike at them at once.”
Whereupon Yuan Shang rode out to battle. His brother Yuan Tan, seeing him come with fifty thousand troops, knew that his treachery had been discovered, so he also took the field. When the forces were near enough, Yuan Tan opened on Yuan Shang with a volley of abuse.
“You poisoned my father and usurped the succession; now you come out to slay your elder brother?”
The battle went against Yuan Tan. Yuan Shang himself took part in the fight, risking the arrows and the stones. He urged on his troops and drove his brother off the field. Yuan Tan took refuge in Pingyuan. Yuan Shang drew off his army to his own city.
Yuan Tan and Guo Tu decided upon a new attack, and this time they chose General Cen Bi as Leader of the Van. Yuan Shang went to meet him. When both sides had been arrayed and the banners were flying and the drums beating, Cen Bi rode out to challenge and railed at his opponent. At first Yuan Shang was going to answer the challenge himself, but Lu Kuang had advanced. Lu Kuang and Cen Bi met but had fought only a few bouts when Cen Bi fell. Yuan Tan's soldiers were once more defeated and ran away to Pingyuan. Shen Pei urged his master to press for the advantage, and Yuan Tan was driven into the city, where he fortified himself and would not go out. So the city was besieged on three sides.
Yuan Tan asked his strategist what should be done next, and Guo Tu said, “The city is short of food, the enemy is flushed with victory, and we cannot stand against them. My idea is to send some one to offer surrender to Cao Cao and thus get him to attack Jizhou. Your brother will be forced to return thither, which will leave you free to join in the attack. We may capture Yuan Shang. Should Cao Cao begin to get the better of your brother's army, we will lend our force to help Yuan Shang against Cao Cao; and as Cao Cao's base of supply is distant, we shall drive him off. And we can seize on Jizhou and begin our great design.”
“Supposing this scheme be attempted, who is the man for a messenger?”
“I have one Xin Pi, Xin Ping's younger brother; he is the magistrate here in this very place. He is a fluent speaker and good scholar and suited to your purpose.”
So Xin Pi was summoned and came readily enough. Letters were given him and an escort of three thousand soldiers took him beyond the border. He traveled as quickly as possible.
At that time Cao Cao's camp was at the Xiping Pass and he was attacking Liu Biao, who had sent Liu Bei out to offer the first resistance. No battle had yet taken place.
Soon after his arrival, Xin Pi was admitted to the Prime Minister's presence; and after the ceremonies of greeting, Cao Cao asked the object of the visit. Xin Pi explained that Yuan Tan wanted assistance and presented his dispatches. Cao Cao read them and told the messenger to wait in his camp while he called his officers to a council.
The council met. Cheng Yu said, “Yuan Tan has been forced into making this offer because of the pressure of his brother's attack. Put no trust in him.”
Lu Qian and Man Chong said, “You have led your armies here for a special purpose; how can you abandon that and go to assist Yuan Tan?”
“Gentlemen, not one of you is giving good advice,” interposed Xun You. “This is how I regard it. Since there is universal trouble, in the midst of which Liu Biao remains quietly content with his position between the River Zhang and the River Han, it is evident that he has no ambition to enlarge his borders. The Yuans hold four regions and have many legions of soldiers. Harmony between the two brothers means success for the family, and none can foresee what will happen in the empire. Now take advantage of this fraternal conflict and let them fight till they are weakened and have to yield to our Prime Minister. Then Yuan Shang can be removed, and when the times are suitable, Yuan Tan can be destroyed in his turn. Thus peace will ensue. This present combination of circumstances is to be taken advantage of to full measure.”
Cao Cao realized the truth of this and treated Xin Pi well.
At a banquet Cao Cao said, “But is this surrender of Yuan Tan real or false? Do you really think that Yuan Shang's army is sure to overcome him?”
