 On 1 May an even larger operation , known by the ARVN as Operation Toan Thang 43 and by MACV as Operation Rockcrusher , got underway as 36 B @-@ 52s dropped 774 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 Cav 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. airmobile units that had been lifted in by helicopter . 
