Cpl. Truesdale was second in command of a Guardia Nacional Patrol in active operations against armed bandit forces in the vicinity of Constancia, near Coco River, northern Nicaragua, on 24 April 1932. While the patrol was in formation on the trail searching for a bandit group with which contact had just previously been made, a rifle grenade fell from its carrier and struck a rock, igniting the detonator. Several men close to the grenade at the time were in danger. Cpl. Truesdale, who was several yards away, could easily have sought cover and safety for himself. Knowing full well the grenade would explode within two or three seconds, he rushed for the grenade, grasped it in his right hand, and attempted to throw it away from the patrol. The grenade exploded in his hand, blowing it off and inflicting serious multiple wounds about his body. Cpl. Truesdale, in taking the full shock of the explosion himself, saved the members of the patrol from loss of life or serious injury.