The first 100,000 U.S. troops under General Pershing were headed to the front lines as Harry spent his first days in France. Here he learned to fire the “French 75”—World War I’s most heralded gun. It could blast a 75-millimeter shell 4.25 miles, at a rate of fifteen rounds per minute. The gun weighed more than three thousand pounds, and rolled on pneumatic tires, so it could be towed into position by car or horse from one battlefield to the next. It required an understanding of trajectory theory as well as mechanics.
