AP caption reads: "Air cavalrymen use a huge B-52 bomb crater as their home on the fringes of the A Shau Valley during Operation Delaware in Vietnam, April 26, 1968. They also use the pit as a firing point for an 82mm mortar. Before Allied troops moved into the valley for the first time in two years, the area has been softened up by hundreds of heavy air strikes. From this point, men of the 1st Cavalry will move further into the valley in search of North Vietnamese. The valley is the largest enemy supply base in the south and is the terminus of infiltration routes coming in from the north through Laos. (AP Photo/Eddie Adams)"