尊室說
To solve the bandit problems in the borderlands, Đoàn Thọ was appointed as President of Tonkin military service. When Đoàn Thọ arrived at Lạng Sơn, a bandit named Tô Tứ sneaked on Lạng Sơn at midnight and killed Đoàn Thọ, while Võ Trọng Bình fled. In 1870, the Vietnamese court immediately assigned Hoàng Kế Viêm as governor of Lạng Sơn, Thái Bình and Ninh Bình to suppress banditry in northern Vietnam together with Tôn Thất Thuyết.