The 13th Group Army was established in 1985 after the disbandment of the 50th Army. It incorporated the 149th Division, which had been part of the 50th Army. During the Sino-Vietnamese War, the Kunming Military Region took responsibility for Chinese operations during the Battle of Lào Cai, which involved the 11th and 13th Armies from the Kunming Military Region itself, and the 14th Army from the Chengdu Military Region, totalling about 125,000 troops. The three armies was followed by the reserve 149th Division of the 50th Army, as well as many support units. The invasion comprised three prongs of advances: while the 11th Army was assigned to attack Phong Thổ before hooking up to Sapa and Lào Cai from the west, the 14th Army was ordered to take Mường Khương and move against Lào Cai from the