In the Korean War, a horse named Reckless worked alongside U.S. Marines to carry heavy ammunition to the front lines. During one battle, Reckless made 51 trips to the front lines in a single day, and even brought wounded soldiers back to the base camp. Today, horses, donkeys, and mules help Marines who are fighting in the mountains of Afghanistan. These animals can move across rough, rocky terrain that trucks and Humvees cannot negotiate. In this...