[3] On a day in spring 831, when Li Zaiyi was feasting with an imperial messenger, Yang Zhicheng and a group of soldiers he gathered started a disturbance.
Li Zaiyi and his son fled to Yi Prefecture (易州, in modern Baoding, Hebei), in neighboring Yiwu Circuit (義武).
As part of his takeover, Yang also killed the prefect of Mo Prefecture (莫州, in modern Cangzhou, Hebei), Zhang Qingchu (張慶初).
Emperor Wenzong thus allowed Yang to remain in control of the circuit and made him acting military governor (留後, Liuhou).
[4] As of 833, in addition to being military governor, Yang Zhicheng also carried the honorary title of acting minister of public works (工部尚書, Gongbu Shangshu).