Instead of Marines humping up mountains, the whirlybirds set them down on top, and the Marines chased the NVA, gaining momentum from the slopes of the hills. Terrain was no longer an obstacle. The Marine mobility posture caught the enemy unaware and kept him on the move. Once landed on a mountaintop, an LZ was established and Marine choppers ferried in artillery support. It was Nguyen's turn in the barrel, but Marines knew it wasn't over . . .
Marines are still under the gun.
When word was passed to halt and set up a defense, Marines shrugged off their packs, placed their weapons nearby and immediately began digging in. When Nguyen's guns opened up from the DMZ, Marines caught in the open were targets for shrapnel and hurtling rocks. Others, transported to mountain observation posts by helicopter, maintained a constant vigil on the Ho Chi Minh trail or other routes of infiltration. And as the Marines moved and neutralized, they modernized. Terrain in Vietnam limited the use of armored columns, but the guns on armored vehicles lent a definite advantage to Marines.