After Guo Huai died in 255, Chen Tai succeeded him and took charge of military affairs in the Guanzhong region. During this time, Jiang Wei led the Shu forces to attack Wei and aimed to capture Didao. Chen Tai ordered Wang Jing, the Inspector of Yong Province, to defend Didao and guard the fortress while waiting for reinforcements. However, Wang Jing, in his eager to gain glory, led the troops out of Didao to attack the enemy at Gu Pass, where he suffered a defeat and was forced to return to Didao with only 10,000 men. Wang Jing then focused on defending Didao, as Chen Tai instructed him. Upon hearing news of Wang Jing's defeat, Chen Tai quickly mobilised his troops to come to Wang Jing's aid. However, he was also worried that Jiang Wei would use the opportunity to attack the Wei army's supply depot at Liyang in the east, and that Jiang Wei would recruit the Qiang tribesmen to join the Shu army and pose an even greater threat. To his relief, Jiang Wei did not do so and instead concentrated his attacks on Didao and besieged the fortress. Wei forces led by Deng Ai, Wang Bi and Hu Fen came to join Chen Tai's army. Jiang Wei predicted correctly that Wei reinforcements would come to Didao, so he had ordered some units to ambush the reinforcements when they showed up. However, Chen Tai and his army took another route through the mountainous terrain and arrived in the hills southeast of Didao, completely bypassing the other route laden with ambushes. Jiang Wei attacked Chen Tai on the hills but Chen Tai drove him back easily because the mountainous terrain was to his advantage. As more Wei reinforcements approached Didao, Jiang Wei realised that the siege could not last any longer so he pulled back the Shu forces and retreated to Zhongti by October or November 255.