Shen Pei and Peng Ji declared Yuan Shang successor with the titles of Regent Marshal and Supreme Imperial Protector of the four regions of Jizhou, Qingzhou, Youzhou, and Bingzhou and sent in a report of the death of the late Imperial Protector.

At this time Yuan Tan, the eldest son, had already marched out his army to oppose Cao Cao. But hearing of his father's death, he called in Guo Tu and Xin Ping to consult as to his course of action.

"In your absence, my lord," said Guo Tu, "the two advisers of your younger brother will certainly set him up as lord, wherefore you must act quickly."

"Those two, Shen Pei and Peng Ji, have already laid their plans," said Xin Ping. "If you go, you will meet with some misfortune."

"Then what should I do?" asked Yuan Tan.

Guo Tu replied, "Go and camp near the city, and watch what is taking place while I enter and inquire."

Accordingly Guo Tu entered the city and sought an interview with the young Imperial Protector.

"Why did not my brother come?" asked Yuan Shang after the usual salutes.

Guo Tu said, "He cannot come as he is in the camp unwell."

"By the command of my late father, I take the lordship. Now I confer upon my brother the rank of General of the Flying Cavalry, and I wish him to go at once to attack Cao Cao, who is pressing on the borders.I will follow as soon as my army is in order."

"There is no one in our camp to give advice," said Guo Tu. "I wish to have the services of Shen Pei and Peng Ji."

"I also need the help of these two," said Yuan Shang. "And as I am always working at schemes, I do not see how I can do without them."

"Then let one of these two go," replied Guo Tu.

Yuan Shang could do no other than accede to this request, so he bade the two men cast lots who should go.Peng Ji drew the lot and was appointed, receiving a seal of office. Then he accompanied Guo Tu to the camp. But when he arrived and found Yuan Tan in perfect health, he grew suspicious and resigned.

Yuan Tan angrily refused to accept his resignation and was disposed to put him to death, but Guo Tu privately dissuaded him, saying, " Cao Cao is on the borders, and Peng Ji must be kept here to allay your brother's suspicions.After we have beaten Cao Cao, we can at once make an attempt on Jizhou."

Yuan Tan agreed and forthwith broke up his camp to march against the enemy. He reached Liyang and lost no time in offering battle.