During the PAVN's Easter Offensive) of 1972, he was given command of I Corps, replacing the disgraced Lieutenant General Hoàng Xuân Lãm. General Trưởng held PAVN forces at bay before Huế and then launched (against the initial resistance of President Nguyễn Văn Thiệu and MACV) Operation Lam Son 72. During the counteroffensive, he successfully pushed PAVN forces back to the city of Quang Tri (which was retaken in September) and advanced on to the Cửa Việt river.