In spring 822, with Shen Prefecture in desperate straights, the imperial government capitulated and commissioned Wang the military governor of Chengde, sending the official Han Yu to announce the commission and to persuade Wang to allow Niu to leave.
After the imperial generals Li Guangyan and Wu Chongyin captured the Zhangyi outpost Lingyun Fence (陵雲柵, in modern Luohe, Henan) in fall 816, however, Li became apprehensive and submitted a petition offering to submit.