By this time, the Tang generals Guo Ziyi and Li Guangbi had fought their way into Emperor An's territory north of the Yellow River, cutting off the communication between Luoyang and Fanyang, causing much fear in An's troops. An considered withdrawing north of the Yellow River to secure the territory, but meanwhile, suspicions had begun to rise between Yang Guozhong and Geshu, each believing that the other had designs on himself. Yang therefore persuaded Emperor Xuanzong to order Geshu to attack the Yan general Cui Qianyou, who was then stationed at Shan Commandery. (This order was against the advice of Geshu, Guo, and Li Guangbi that the proper strategy was to secure Tong Pass and let Guo and Li Guangbi capture the Yan territory to the north.) Geshu, with Emperor Xuanzong repeatedly ordering him to attack, was forced to do so, and was defeated by Cui. Geshu's subordinate Huoba Guiren () seized him and surrendered to Yan forces. Subsequently, An induced Geshu to write letters to several Tang generals, urging them to surrender, but they all refused.