By early 1971, North Vietnamese troop strength in the Base Area 604 area was estimated by U.S. intelligence at 22,000 men: 7,000 combat troops, 10,000 personnel in logistical and support units, and 5,000 Pathet Lao, all under the command of the newly created 70th Front [REF].
The mission of the ARVN central column was to advance down the valley of the Se Pone River, a relatively flat area of brush interspersed with patches of jungle and dominated by heights to its north and the river and more mountains to the south.