Operation Hump was a search and destroy operation by US and Australian forces in November 1965. The objective was to drive out Viet Cong  units who had taken up positions on several key hills about 17.5 miles north of Bien Hoa

Official reports claimed that the 173rd Airborne Brigade had killed about 400 VC by body count and another 200 estimated dead while U.S. casualties were 49 killed and 83 wounded. The figure of 400 VC killed turned out to be a guess made in the immediate aftermath of the battle under pressure from Military Assistance Command, Vietnam headquarters. Later appraisals that raised the count to 700 are suspect as well. 

Source: Wikipedia