 In the II Corps area , Operation Binh Tay I ( Operation <unk> the West ) was launched by the 1st and 2nd Brigades of the U.S. 4th Infantry Division and the 40th ARVN Infantry Regiment against Base Area 702 ( the traditional headquarters of the communist B @-@ 2 Front ) in northeastern Cambodia from 5 – 25 May . Following airstrikes , the initial American forces , assaulting via helicopter , were driven back by intense anti @-@ aircraft fire . On the following day , the 3rd Battalion , <unk> Infantry ( on loan from the U.S. 101st Airborne Division ) , landed without opposition . Its sister unit , the 1st Battalion , 14th Infantry was also unopposed . The 3rd Battalion of the 8th Infantry , however , inserted only 60 men before intense PAVN fire ( which shot down one helicopter and damaged two others ) shut down the landing zone , leaving them stranded and surrounded overnight . By the following morning , PAVN forces had left the area . 
