Niu Sengru
In 831, when Li Zaiyi was feasting with an imperial emissary, his officer Yang Zhicheng started a mutiny, and Li Zaiyi and his son Li Zhengyuan () were forced to flee to Yi Prefecture (易州, in modern Baoding, Hebei) (in neighboring Yiwu Circuit (). Emperor Wenzong initially considered launching an army to reinstate Li Zaiyi, but the chancellor Niu Sengru pointed out that the imperial government had no strength at the time for such a campaign. Emperor Wenzong thus allowed Yang to take over (although, at that time, only naming Yang acting military governor). Meanwhile, when Li Zaiyi arrived in Chang'an from Yi Prefecture, Emperor Wenzong, because Li Zaiyi had been respectful and had participated in the campaign against Henghai, continued to let him carry the title "Tong Zhongshu Menxia Pingzhangshi", and further conveyed the title of "Taibao" (太保, one of the Three Excellencies) on him.