Although the U.S. Army had established a Tank Corps during World War I, research and development into new armored fighting vehicles languished in the following two decades. But in the summer of 1940, with the likelihood of U.S. entry into World War II increasing almost daily, the War Department acknowledged the importance armor would play in future conflicts by establishing the Armored Force on July 10, 1940. Fort Knox, already home to mechanized Cavalry units, was chosen as the headquarters for this new component of the U.S. Army.
To guide the new organization in the nascent stage of its development, the Army selected Adna R. Chaffee, Jr., who had been one of the most vocal proponents of mechanization in the Cavalry during the interwar years. As commander of the 7th Cavalry Brigade (Mechanized), Chaffee put his theories regarding the role of armor and mechanized units into practice during the First Army maneuvers of 1939. Leading his unit on an overnight sixty-mile road march (in blacked-out conditions), Chaffee culminated the “end run” by unleashing a flanking attack at dawn that saw the forces of 7th Cavalry swarm into the rear of the opposing force, swiftly ending the maneuvers and validating many of Chaffee’s doctrines.
If Chaffee’s resounding success in the 1939 maneuvers were not enough to convince the Army of the need for a distinct system of developing armor technology and training Soldiers to use it, then the German victory over France in May, 1940 most certainly sealed the deal. Although Germany had launched its largest and most noticeable attack against Belgium, the knockout blow was delivered by armor spearheads that sliced through the Ardennes forest before advancing to the Channel ports to seal off hundreds of thousands of Allied troops.
Sadly, Chaffee died before he could put his tactics and strategies to use in defeating the Germans in World War II, but his contributions to the development of Armored doctrine were memorialized by the British when they named the U.S. Light Tank M24 the “Chaffee” in his honor.