 The only conventional battle fought by American troops occurred on 1 May at the town of <unk> , the suspected terminus of the Sihanouk Trail at the junction of Routes 7 , 13 , and 131 . Elements of the U.S. 11th Armored Cavalry and supporting helicopters came under PAVN fire while approaching the town and its airfield . When a massed American attack was met by heavy resistance , the Americans backed off , called in air support and blasted the town for two days , reducing it to rubble . During the action , Brigadier General Donn A. <unk> , commander of the 11th Armored Cavalry , was wounded by grenade fragments and evacuated . 
