Historical Note: The Củ Chi tunnel network stretched over 250 km beneath South Vietnam and served as the Viet Cong's operational base for the 1968 Tết Offensive. "Tunnel rats" — volunteers, usually under 5'6" — entered with only a pistol, knife, and flashlight. The 25th Infantry Division ("Tropic Lightning"), headquartered at Củ Chi, conducted major tunnel-clearing operations throughout 1966–1969. Illustrations below are artist recreations based on historical photographs from the era.