In the seventy years that have passed since the tank first appeared, antitank combat has presented one of the greatest challenges in land warfare. Dramatic improvements in tank technology and doctrine over the years have precipitated equally innovative developments in the antitank field. One cycle in this ongoing arms race occurred during the early years of World War II when the U.S. Army sought desperately to find an antidote to the vaunted German blitzkrieg. This Leavenworth Paper analyzes the origins of the tank destroyer concept, evaluates the doctrine and equipment with which tank destroyer units fought, and assesses the effectiveness of the tank destroyer in battle.