Cavalry refers to soldiers who fight while riding on horseback. For thousands of years, cavalry units were among the most powerful and feared forces in any army. Mounted soldiers could move quickly across battlefields, charge into enemy lines with devastating force, and scout ahead to gather information about opposing forces.

The advantage of cavalry was speed and mobility. While foot soldiers might march fifteen miles in a day, cavalry could cover twice that distance. A cavalry charge, with hundreds of horses thundering forward at full gallop, could break through enemy formations and turn the tide of battle. Famous cavalry units include the Mongol horsemen who conquered much of Asia, the knights of medieval Europe, and the U.S. Cavalry, which played a major role on the American frontier.

By World War I, horses became too vulnerable to machine guns and artillery, and armies began replacing cavalry with tanks and armored vehicles. Today's military forces still use the term cavalry for fast-moving units, but they ride in helicopters or armored vehicles instead of on horses. When someone says “the cavalry is coming,” they mean help or reinforcements are on the way, just as soldiers once felt relief seeing friendly cavalry arriving at a crucial moment.