 On 1 May an even larger operation , known by the ARVN as Operation Toan Thang 43 and by MACV as Operation <unk> , got underway as 36 B @-@ <unk> dropped <unk> tons of bombs along the southern edge of the Fishhook . This was followed by an hour of massed artillery fire and another hour of strikes by tactical fighter @-@ bombers . At 10 : 00 , the 1st Air <unk> Division , the 11th Armored Cavalry Regiment , the 1st ARVN Armoured Cavalry Regiment , and the 3rd ARVN Airborne Brigade then entered Kampong Cham Province of Cambodia . Known as Task Force Shoemaker ( after General Robert M. Shoemaker , the Assistant Division Commander of the 1st Cavalry Division ) , the force attacked the long @-@ time communist stronghold with 10 @,@ 000 U.S. and 5 @,@ 000 South Vietnamese troops . The operation utilized mechanized infantry and armored units to drive deep into the province where they would then link up with ARVN airborne and U.S. <unk> units that had been lifted in by helicopter . 
