Tôn Thất Thuyết
Phan was transferred to the Huế court as a member of the censorate, a watchdog body that monitored the work of the mandarinate. He earned the ire of many of his colleagues, but the trust of the emperor, by revealing that the vast majority of the court mandarins were making a mockery of a royal edict to engage in regular rifle practice. Tự Đức later dispatched Phan on an inspection trip to northern Vietnam. His report led to the ousting of many officials who were deemed corrupt or incompetent, including the viceroy of the northern region. He rose to become the Ngu Su, or Imperial Censor, a position which allowed him to criticise other high officials and even the emperor for misconduct. Phan openly criticised Tôn Thất Thuyết, the foremost mandarin of the court, believing him to be rash and dishonest. Aside from his work in rooting out corruption, Phan also compiled a historical geography of Vietnam, which was published in 1883.