U.S. Marines emerge from their foxholes south of the DMZ after a third night of fighting against North Vietnamese troops, September 1966. The helicopter at left was shot down when it came in to resupply the unit.

U.S. paratroopers of the 2nd Battalion, 173rd Airborne Brigade, hold their automatic weapons above water as they cross a river in the rain during a search for Vietnamese liberation troops positions in the jungle area of Ben Cat, September 25, 1965.

This photo shows hovering U.S. Army helicopters pour machine-gun fire into the tree line to cover the advance of South Vietnamese ground troops as they attack a camp of Vietnamese liberation troops eighteen miles north of Tay Ninh, near the Cambodian border, March 1965.

An unidentified American with an anti-war message on his helmet.

A medic treats an American soldier during a firefight despite having a bandage around one of his own eyes, right.

A wounded paratrooper grimaces in pain as he awaits medical evacuation from base camp in the A Sau Valley.

The body of a U.S. paratrooper in the jungle near the Cambodian border is lifted up to an evacuation helicopter in War Zone C, May 14, 1966.

A makeshift underground hospital at the besieged Khe Sanh Marine base, March 1968.

Freshly landed U.S. Marines make their way through the sands of Red Beach at Da Nang, April 10, 1965.

A group of paratroopers.

An aerial image shows a large peace sign, apparently gouged out of the countryside with a bulldozer, near Camp Eagle, headquarters of the 101st Airborne Division, in the northern part of South Vietnam, May 8, 1971.

As fellow troopers help wounded comrades, a paratrooper of A Company, 101st Airborne Division, guides a medevac helicopter through the jungle foliage to pick up casualties suffered during a five-day patrol near Hue, in April 1968.