of arrows； bolts and stones from the walls that the besiegers dared not close in。
Suddenly from the midst of the Wei army came the roar of a bomb； soon followed by others from different places。 The soldiers were startled； but no one could say whence the sounds had proceeded。 Guo Huai went to search the wheat fields； and then the four armies from the corners of the city converged upon the Wei army。 At the same time the defenders burst out of the city gates； and a great battle began。 Wei lost many troops。
After heavy fighting Sima Yi extricated his army from the battle and made his way to a hill； which he set about holding and fortifying； while Guo Huai got round to the rear of the city and called a halt。
Zhuge Liang entered the city and sent his troops to camp again at the four corners of the walls。
Guo Huai went to see his chief； and said； 〃We have long been at grips with these soldiers and are unable to drive them off。 We have now lost another fight。 Unless something is done； we shall not get away at all。〃
〃What can we do？〃 asked Sima Yi。
〃You might write to Yongzhou and Liangzhou to send their forces to our help。 I will try my fortune against Saber Pass and cut off Zhuge Liang's retreat and supplies。 That should bring about discontent and mutiny； and we can attack when we see the enemy in confusion。〃
The letters were sent； and soon Sun Li came leading the troops of Yongzhou and Liangzhou； foot and horse； of two hundred thousand。 The new arrivals were sent to help Guo Huai in the attack on Saber Pass。
After many days had passed without sight of the enemy； Zhuge Liang thought it was time to make another move。
Calling up Jiang Wei and Ma Dai； he said； 〃The soldiers of Wei are well posted on the hills and ref