Tian Hongzheng
With Emperor Xianzong also having declared the military governor of Chengde Circuit, Wang Chengzong, a renegade — but not declared a campaign against Wang at that point — Tian Hongzheng led his troops to wait on the border with Chengde, and Wang repeatedly harassed his troops. Tian Hongzheng requested permission to enter Chengde territory, and Emperor Xianzong authorized him to advance to Bei Prefecture (貝州, in modern Xingtai). It was also said that it was because of Tian's loyalty to the imperial government that the military governor of Pinglu, Li Shidao, did not dare to openly aid Zhangyi. After Wu was defeated and captured by the imperial general Li Su in 817, Wang became fearful, and he made offers through Tian to submit to the imperial government. Tian relayed Wang's offers to the imperial government, and in spring 818, Emperor Xianzong accepted Wang's offer to send his sons Wang Zhigan () and Wang Zhixin () to the capital Chang'an as hostages and to submit two of Chengde's six prefectures to imperial control.