Giant artillery tractor used by U.S. Marines ... Chug-chugging over seemingly impassable roads and negotiating steep hills under adverse conditions, the gasoline tractor used by U.S. Marines, hauls heavy artillery pieces from place to place with little effort. Perhaps you didn't know that Marines are artillerymen. Yes, indeed! They are infantrymen too, as well as signalmen, engineers and aviators . ... Photo provided by the U.S. Marine Corps recruiting station ...