Tanks of the United States

• 1. Introduction

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  Tanks of the United States have a story that begins not with American ingenuity, but with borrowed French blueprints and the urgent reality of a war already in progress. When General John Pershing, commanding the American Expeditionary Forces, read a report on British and French tank operations in 1917, he concluded that both light and heavy tanks were essential and had to be acquired as quickly as possible. The U.S. had no tanks of its own when it entered the First World War in April 1917. What followed was a century of design, doctrine, and hard-learned battlefield lessons that would shape armored warfare across the globe. How did a nation that entered its first great war without a single tank become one of the most influential forces in armor design? And what did the men who trained in those first crude machines go on to build?

• 2. America's First Tanks

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  The Inter-Allied Tank Commission made a practical decision in 1917: rather than wait for new designs, the fastest way to arm American forces was to manufacture the French Renault FT light tank on U.S. soil. The resulting vehicle, called the Six Ton Tank M1917, became the first American mass-produced tank, a near-copy built under license. The Army ordered approximately 4,440 of them between 1918 and 1919, but the project ran into trouble almost immediately. French specifications were written in metric, incompatible with American machinery. Coordination between military departments, suppliers, and manufacturers was poor. The Army in France expected the first 300 vehicles by April 1918; production had not even started by June. Only about 950 were ever received before the contract was canceled, and the first two did not arrive in France until the 20th of November 1918, nine days after the armistice. Meanwhile, Ford launched a parallel effort with the 3-Ton M1918, a two-man tank powered by twin Model T engines and armed with a machine gun. A contract for 15,000 was awarded, but the Tank Corps found the design unsatisfactory. When the armistice came, only fifteen had been built.

• 3. Eisenhower, Patton, and the Doctrine Debate

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  Captain Dwight Eisenhower arrived at Camp Meade, Maryland, in February 1918 with the 65th Engineer Regiment, tasked with standing up the Army's first heavy tank battalion. When his unit shipped out on the night of the 26th of March, Eisenhower did not go with them. His superiors recognized his administrative talent and instead assigned him to establish the Army's primary tank training center at Camp Colt in Gettysburg, Pennsylvania, on the very ground of Pickett's Charge. He trained crews there with trucks that had machine guns bolted down, because the actual tanks had not yet arrived. In France, Captain George S. Patton was the first officer assigned to train tank crews on the other side of the Atlantic. After the war, both men ended up at Camp Meade, where they worked alongside each other under General Rockenbach's command. Together, Patton and Eisenhower developed theory and doctrine for using tanks in mass formations to achieve breakthroughs and flanking attacks. Senior army officers pushed back hard, insisting tanks should support the infantry rather than operate as an independent arm. Congress sided with the traditionalists. The National Defense Act of 1920 dissolved the Tank Corps and placed tanks under infantry control. Patton, convinced there was no future in tanks under that arrangement, transferred to the cavalry in September 1920. Eisenhower left the tank world in January 1922, assigned to an infantry brigade in Panama. The debate they had started, however, would eventually be settled on the battlefields of the next world war.

• 4. Interwar Constraints and Experiments

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  The 1920 legislation created a frustrating bind: tanks legally belonged to the infantry, but cavalry units wanted armored vehicles too. The solution was a workaround in language. Tanks developed for the cavalry were labeled "combat cars" rather than tanks, which allowed the cavalry to acquire them without violating the law. By 1940, the designation was dropped and the M1 combat car was simply redesignated the light tank M1A2. The War Department's weight limits made life difficult for designers. The light tank was not to exceed 5 tons so it could be transported by truck. The medium tank was capped at 15 tons to fit on railroad flatcars. In reality, it proved impossible to build a 15-ton vehicle that met all the Army's requirements. By 1926, the General Staff reluctantly approved development of a 23-ton design, while insisting engineers keep trying to hit the 15-ton target. The real turning point came in 1928, when Secretary of War Dwight F. Davis watched British experimental armored force maneuvers and directed the Army to develop a similar tank force. An experimental mechanized force assembled at Camp Meade from the 1st of July to the 20th of September that year, drawing on infantry, cavalry, artillery, the Air Corps, engineers, and medical units. The experiment was not repeated in 1929 due to insufficient funds and obsolete equipment, but it produced a recommendation for a permanent mechanized force. Auto engineer J. Walter Christie's experimental tank designs were tested during this period. None were adopted, usually because they exceeded Army branch standards, but Christie's ideas on suspension and mobility proved influential in many countries and eventually shaped U.S. thinking as well.

• 5. World War II: Mass Production at Scale

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  The Battle of France in the summer of 1940 clarified everything. U.S. observers watched British and French light tanks get decimated by German Panzers, and the Army moved quickly. Work on a new light tank based on the M2 series began in July 1940, leading to the M3 Stuart. Production of the M3 and its successor the M5 ran from March 1941 to October 1943, yielding a total of 25,000 vehicles. Of 6,258 M3 medium tanks built, 2,855 went to the British Army and about 1,368 to the Soviet Union. The British named their American tanks after Civil War generals: the M3 medium became the Grant and Lee, the M4 medium became the Sherman. The M4 Sherman's design requirements were drawn up to keep the five-man crew, mount a 75 mm gun in a fully rotating turret, and use the same engine, transmission, tracks, and suspension as the M3 Lee to simplify production. The Army accepted the T6 pilot model and ordered production of the M4 on the 5th of September 1941. Chrysler opened the Detroit Arsenal Tank Plant specifically to build tanks; the original contract for 1,000 M2 medium tanks was revised before production even began to build M3 Grants instead. Seven main sub-designations of the Sherman were produced concurrently at different plants, differing mainly in engine type. The Sherman was not the most heavily armored or best-gunned tank of the war, but it was reliable, cheap to produce, and available in enormous numbers. When German Tiger and Panther tanks began appearing in force, the Army fitted later Shermans with a 76 mm high-velocity gun, accepted into production in January 1944. The M4A3E2 Jumbo, a limited run of 254 tanks accepted in June and July of 1944, had armor at some points exceeding 7 inches in effective thickness, specifically to assault the fortifications at Normandy. At the other end of the weight scale, the M26 Pershing arrived late in the war, with its 90 mm main gun. Of 2,222 produced beginning in November 1944, only 20 saw combat in Europe during the Second World War.

• 6. Tank Destroyers and Support Vehicles

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  Alongside conventional tanks, the U.S. Army developed a separate family of tracked vehicles designated Gun Motor Carriages. These tank destroyers sacrificed crew protection for firepower, mounting larger guns in open-topped turrets on tank-derived hulls. The M18 Hellcat earned a distinction that lasted well into the Cold War: it was the fastest armored vehicle in the American inventory until the turboshaft-powered M1 Abrams appeared decades later. That speed came from minimizing armor to no more than one inch thick and powering the vehicle with a radial engine originally designed for aircraft. The M36 Jackson mounted a 90 mm gun on a hull derived from the M10 tank destroyer, which itself used the reliable M4 Sherman chassis. The M36 first saw combat in Europe in October 1944 and later served in Korea, where it could defeat any Soviet tank fielded in that conflict. Some M36s supplied to Yugoslavia continued operating into the 1990s. For close fire support, the M8 howitzer motor carriage, nicknamed the Scott, mounted a 75 mm howitzer on an M5 Stuart hull. It could travel at 36 mph on roads, was crewed by four, and was effective against bunkers and fixed positions. It later appeared in the First Indochina War and the Algerian War.

• 7. Korea, Cold War, and the Evolution Continues

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  When North Korea invaded in 1950, the first American armor to respond was the M24 Chaffee, drawn from occupation troops in Japan who were underequipped and inexperienced after rapid post-war demobilization. The M24 fared poorly against the North Korean T-34-85, losing most of their number while inflicting little damage. The tanks that turned the situation around were heavier: the M4A3 Sherman, the M26 Pershing, and especially the M46 Patton. The M46 was itself a reworking of the Pershing: its engine had been found inadequate for a medium tank because the M26 carried an extra ten tons compared to the M4A3 but used the same powerplant. The Continental AV1790-3 engine chosen for the M46 produced more than 800 hp, compared to the M26's engine rated for 500 hp. The first M46 Pattons were deployed to South Korea on the 8th of August 1950. By the end of that year, 200 M46 Pattons had been fielded, forming about 15 percent of U.S. tank strength in Korea; the balance of 1,326 tanks shipped during 1950 included 679 M4A3 Shermans, 309 M26 Pershings, and 138 M24 Chaffees. The M103 heavy tank, accepted into service in 1957, was built to counter Soviet heavy tanks with its long-range 120 mm cannon. Of 300 built, most went to the Marine Corps. When the Army received the M60 series main battle tanks in 1960, heavy armor was retired from Army inventory; the Marines held on to the M103 until 1973. That transition marked the full acceptance of the main battle tank concept in the United States, replacing the old categories of light, medium, and heavy with a single universal class.