Photo of Trooper attached to a mechanized unit of the U.S. 25th division slowly crawls into Viet Cong tunnel in a weep through the Ho Bo woods north of Saigon, March 18, 1968. This was part of the largest allied offensive of the war, Operation “Quyet Thang” (resolved to win), with some 50,000 men sweeping through the five provinces around the capital City of Saigon. Their objective is to sweep out the remnants of Vietcong units who attacked the city in force during the Tet offensive. This “tunnel rat” as he is called, is a volunteer who checks out tunnels after initial grenades or smoke attacks. In this tunnel nothing was found.

A “tunnel rat” trooper ventures into a Viet Cong tunnel in the Ho Bo woods in 1968. Bunkers, spider holes, and small cavernous openings often led to deadly underground mazes where Viet Cong fighters lurked in ambush. (AP Photo/Joe Holloway Jr)

AP Photo/Joe Holloway Jr