Army Combat Branches: Armor. The motto of the U.S. Army's armor branch is “The Combat Arm of Decision.” Equipped with tanks and supported by infantry, artillery, helicopters, and air forces, armor units close with and destroy enemy forces using maneuver, protected firepower, and shock.

Though armor only became a separate branch with the U.S. Army Reorganization Act of 1950, American armor saw combat during World War I. Inspired by British and French tanks, Gen. John J. Pershing in 1916 approved plans for an overseas U.S. Army Tank Corps. On 10 November 1917, Capt. George S. Patton, Jr., became the first soldier assigned to the new Tank Corps, which would be headed by Col. Samuel D. Rockenbach. During the war, 1,235 officers and 18,977 enlisted men served in the Tank Corps, two‐thirds of their overseas forces. While Patton organized the light tank school and its two battalions in France, the 301st Heavy Tank Battalion trained at a British tank school.

Equipped with 144 French‐supplied Renault tanks, Patton's was the first U.S. tank unit into battle on 12 September 1918 in the Battle of St. Mihiel. The U.S. heavy tank brigade first fought on 29 September, using forty‐seven British‐supplied Mark V tanks. American‐made tanks, modified from French and British designs, did not reach Europe during the war.

After World War I, U.S. tank forces all but vanished in the midst of strong and widespread antimilitary sentiments. The National Defense Act of 1920 disbanded the Tank Corps and transferred responsibility for tanks to the chief of infantry who broke the corps into separate tank companies, assigning one per infantry division. During the 1920s, while far‐sighted American officers like Patton, Dwight D. Eisenhower, Daniel Van Voorhis, Robert W. Grow, Bradford G. Chenoweth, and Adna R. Chaffee followed the armor doctrine evolving in Europe through Britain's Basil H. Liddell Hart and J. F. C. Fuller, France's Charles de Gaulle, and Germany's Heinz Guderian, the U.S. War Department viewed tanks simply as support for advancing infantrymen.

In 1931, after becoming chief of staff, Gen. Douglas MacArthur directed each branch of the army to pursue mechanization on its own. The cavalry took over the mechanized force, then at Fort Eustis, Virginia, moved it to Fort Knox, Kentucky, and formed it into the Seventh Cavalry Brigade (Mechanized). It developed annually about two experimental “Combat Cars”—a euphemism for cavalry's light and medium tanks, since the law allowed only the infantry branch to have tanks. These experiments included the high‐speed vehicle developed by J. Walter Christie, which America abandoned but the Soviet Union adopted as the concept behind its highly successful main battle tank of World War II, the T‐34. The U.S. cavalry's M1 and M2 Combat Cars became the basis for the Light Tank M3, the Stuart, which was designed in the spring of 1940 and saw U.S. and British service in World War II. The infantry formed a provisional tank brigade at Fort Benning, Georgia, and carried out its own limited experiments.

On 15 July 1940, in reaction to the stunning German armored successes in Poland and France and its own experiments with armor units, the U.S. War Department created the Armored Force under Chaffee, earning him the title, “Father of the American Armored Force.” The Fort Knox and Fort Benning brigades formed the nuclei for two new armored divisions assigned to an armored corps. From this small beginning, the Armored Force grew during World War II to sixteen armored divisions, which fought in Europe (armor played only a minor role in the Pacific theater). Five armored regiments and 119 tank battalions saw combat. Starting in 1940 with under 1,000 obsolete World War I–era tanks and only 28 new ones, the United States produced nearly 90,000 tanks by 1945. Cavalry units also used tanks. By mid‐1942, the Armored Force had nearly 150,000 men.

The workhorse of U.S. armor units in World War II was the M4 Sherman tank and its numerous variants. This medium tank was relatively fast and agile, combining armored protection, speed, and firepower. It was outmatched, however, by Germany's heavy Panther and Tiger tanks. In February 1945, the United States fielded in Europe the first 20 of 200 T26E3 Pershing heavy tanks, which were nearly a match for the Tiger. The Pershing also saw action on Okinawa in the Pacific.

Additionally, World War II units of thin‐skinned, self‐propelled, fully tracked tank destroyers—created to defeat enemy tanks—peaked in early 1943 at 106 battalions with about 100,000 men. Battlefield experience showed that tanks were superior to the vulnerable tank destroyers, and the U.S. Army abandoned tank destroyers shortly after the war.

Using doctrine that emphasized their mobility, protected firepower, and shock effect, tank units sliced through weak points, dashed around enemy flanks to strike deep into the enemy rear, or sped to plug gaps and blunt attacks. Armor employed in mass proved an effective way to exploit success. The dash of Patton's Third Army across the countryside in the liberation of France in 1944 exemplified these tactics, with the Fourth Armored Division's encirclement of German forces at the city of Nancy in Lorraine, a classic example.

In the Army Reorganization Act (1950), Congress designated armor a new branch. The cavalry was merged into it, and Congress directed that the new branch be considered “a continuation of the cavalry.” The new armor branch assumed responsibility for traditional cavalry missions—reconnaissance, scouting, security, covering force operations, and pursuit, in addition to new missions of penetration, counterarmor, and infantry support.

After World War II the active army divisions were cut from ninety‐two to ten, the sixteen armored divisions down to one. With the outbreak of the Korean War in June 1950, there were no U.S. tanks in the Far East that could match the enemy's Soviet‐made T34s. The first U.S. tanks into Korea were light, thin‐skinned M24 Chaffees. In early August, the United States sent to Korea three hastily cobbled together tank battalions with a hodgepodge of about 200 M4A3E8 Shermans, M26 Pershings, and untested M46 Patton heavy tanks.

By January 1951, there were over 600 American tanks in Korea. At the 1953 armistice, there were also a few new seventy‐five M47 Pattons and T41E (experimental) Walker Bulldog tanks. This mishmash of obsolescent and untested experimental tanks seriously degraded the effectiveness of American armor in the war.

Armor units also fought in the Vietnam War, though they did not play a major role. The main battle tank used in Vietnam was the M48A3 Patton; nearly two were sent there. More important was the lightly armored M551 Sheridan Armored Reconnaissance Airborne Assault Vehicle, which weighed only 16.5 tons and was amphibious and air‐droppable. It fired a guided antitank missile in addition to conventional tank rounds and a special antipersonnel round containing thousands of tiny dartlike flechettes. The Sheridan arrived in Vietnam in 1969; by late 1970, over 200 were issued to almost every ground cavalry unit there. Armor in Vietnam was primarily employed piecemeal and used mainly to clear roads, protect logistical areas, and as reaction forces.

In Europe during the Cold War, both sides expended considerable resources on armored formations. The United States increased its NATO divisions to sixteen (four armored, six mechanized, and six infantry) with three armored cavalry regiments. The 1967 and 1973 Arab‐Israeli wars, where armor played a key role, showed the need for new American equipment, doctrine, and more realistic armor training. The result was the M1 Abrams tank, fielded in 1980, the squad‐carrying Bradley infantry and cavalry fighting vehicle, and other modern battlefield systems key to the execution of the new “AirLand Battle” doctrine. The new doctrine, designed to defeat a Warsaw Pact attack into Central Europe, deemphasized defensive operations and stressed offensive reaction and the combined effects of rapid maneuver, surprise, firepower, and airpower to bypass enemy strengths and to strike deep into the enemy's rear.

During the Persian Gulf War in 1991, the U.S. Army deployed 3 armored divisions and 2 mechanized infantry divisions equipped with nearly 2,000 Abrams tanks and another 1,600 Bradley infantry and cavalry fighting vehicles. The Soviet‐modeled Iraqi Army proved no match for these formations.

By the 1990s, however, the U.S. Army had downsized to ten divisions and two armored cavalry regiments. Among the ten were two armored and four mechanized divisions which contained the remaining twenty‐nine armor battalions. In the twenty‐first century, the armored forces faced an uncertain future, and their usefulness in peacekeeping operations, such as Somalia and the Bosnian Crisis, remained an open question.
[See also Army, U.S.; National Defense Acts (1916, 1920); Tactics: Land Warfare Tactics; Weaponry, Army.]

Bibliography

Timothy K. Nenninger , The World War I Experience, Armor, vol. 78, no. 1 (January–February 1969), pp. 46–51, and The Tank Corps Reorganized, Armor, Vol. 78, no. 2 (March–April 1969), pp. 34–38.
Mary Lee Stubbs and and Stanley Russell Connor , Armor‐Cavalry: Part I: Regular Army and Army Reserve, 1969.
Charles M. Bailey , Faint Praise: American Tanks and Tank Destroyers During World War II, 1983.
Dale E. Wilson , Treat ‘Em Rough!: The Birth of American Armor, 1917–20, 1989.
Robert M. Citano , Armored Forces: History and Sourcebook, 1994.

Steve E. Dietrich