Then Tsʻao became wrathful and bade Chang Liao ride forth as his champion. From the other side rode Chang Ho on a curvetting steed. The two champions fought four or five bouts with no advantage to either. In his heart Tsʻao thought the contest amazing. Then Hsü Chʻu whirled up his sword and went to help. To match him rode out Kao Lan with his spear in rest, and the contestants were now four, battling two and two. Then Tsʻao ordered three companies under Hsiahou Tun and Tsʻao Hung to attack the opponents’ array. Thereupon on Yüan’s side the signal for attack was also given and the legion of crossbow men on the wings shot and the centre archers let fly all together. The arrows flew all over the field in front and Tsʻao’s men could not advance. They hastened away toward the south. Yüan threw his soldiers on their rear and they were broken. They went away toward Kuantu and Yüan advanced another stage. He camped near them. Then Shên Pʻei said, “Now send ten legions to guard Kuantu and get near Tsʻao’s camp, then throw up observation mounds to get a clear view of the enemy and choose vantage points whence to shoot arrows into the midst of their host. If we can force him to evacuate this place we shall have gained a strategical point whence Hsüchʻang can be attacked.” Yüan adopted this suggestion. From each of the camps they sought out the strongest veterans who dug with iron spades and carried earth to raise mounds near Tsʻao’s camp. Tsʻao’s men saw what their enemies were doing and were anxious to make a sortie and drive them off. But the archers and crossbow men came out commanding the narrow throat through which it was necessary to attack and stayed them. At the end of ten days they had thrown up more than half a hundred mounds and on the summit of each was a lofty tower, whence the archers could command their opponents’ camp. Tsʻao’s men were greatly frightened and held up their bucklers to keep off the various missiles. From the mounds the arrows flew down, pang! pang! like a fierce rain. The men of the Yüan army laughed and jeered when they saw their enemies crouching under their shields and crawling on the ground to avoid their missiles. Tsʻao saw that his soldiers were getting out of hand under this attack so he called a council. Liu Yeh spoke up saying, “Let us make ballistæ and so destroy them.” Tsʻao at once had models brought and set cunning workmen to make these machines. They soon constructed some hundreds and placed them along the walls of the camp inside, just opposite the high ladders on the enemy’s mounds. Then they watched for the archers to ascend the towers. As soon as they began to shoot all the ballistæ began to heave their stone balls into the skies and they wrought great havoc. There was no shelter from them and enormous numbers of the archers were killed. Yüan’s men called these machines “Rumblers” and after their appearance the archers dared not ascend the mounds to shoot.