On Oct. 10, 1968, Dennis Pfaff led a patrol of U.S. soldiers through the rice paddies of Vietnam’s Chu Lai area. The men of Bravo Company 4th/21st, 11th Light Infantry Brigade avoided the footpaths and dirt tracks that passed for roads for fear of tripping a land mine. One misstep could take a leg or a life.

The men waded as far as they could through the water before they had to climb up on the bank near the site of an earlier explosion that foundered a tank but injured no one. But when the patrol reached the site of the first explosion, another mine went off.