One of the great battlefield innovations developed by the United States armed forces in its effort to defeat a skilled and often elusive enemy in Vietnam was air cavalry—light infantry deployed by helicopters. While swift-moving aircraft supplanted horse or mechanized ground transport, the theory of rapid deployment of light infantry remained the same. The infantry’s mission is to close with the enemy by means of fire and maneuver to defeat or capture him, or to repel his assault by fire, close combat and counterattack. Only close combat between ground forces gains the decision in battle. Whether on foot, horse or vehicle, parachuting from an aircraft, or jumping from a helicopter, the infantry must maneuver as part of its mission. At all levels of war, successful maneuver requires agility of thought, plans, operations and organizations.