Image from R. P. Hunnicutt’s “Half-Track: A History of American Semi-Tracked Vehicles”, page 158.
Original caption: Below, Sergeant Charles Feider demonstrates compliance with the Geneva Convention restriction on medical personnel using firearms. He was with the Medical Detachment of the 6 Armored Field Artillery Group in Arkansas on 12 November 1942.
In actuality, it was probably just a medic posing with a bow and arrows (I think that’s a quiver on his back?) on his M3 half-track ambulance. Would be a hilarious April Fools vehicle.