De Courcy bestirred himself with the arrival of the autumn campaigning season. The main French effort was made in the west, along the Red River. The Tonkin expeditionary corps undertook a large-scale campaign in October 1885 to capture the Yunnan Army's old base at Thanh May, which had been occupied by Vietnamese insurgents some months earlier. De Courcy concentrated 7,000 troops for the attack on Thanh May, almost as many men as Brière de l'Isle had commanded during the Lạng Sơn campaign in February 1885. An elaborate encircling movement was mishandled, and though the French duly occupied Thanh May, avenging their defeat in the Battle of Phu Lam Tao seven months earlier, most of the brigands escaped the closing pincers and regrouped further up the Red River around Thanh Quan.Huard, 1,072–8; Thomazi, Conquête, 276; Histoire militaire, 125–6
