The Rise and Fall of the American Heavy Tank

American M26 Pershing tanks move through Seoul soon after the South Korean capital was liberated in September 1950. (National Archives)

The heavy tank never found a satisfactory role in the American military. A number of factors such as logistics, economics and evolving military doctrine eventually eliminated it from the formal inventory of the US armed forces in peacetime, but its role in wartime has never diminished.

The heavy tank was defined as a tank with superior armor and lethality to deal with battlefield threats. Survivability, firepower, and mobility were the order of priorities for a heavy tank. Compared to medium tanks whose priorities were lethality, mobility, and survivability, the heavy tank’s emphasis was on survivability and battlefield dominance.

The first American heavy tank, the 43-ton Mark VIII, was similar to the rhomboidal WWI British tanks. It featured an 11-man crew, was armed with two sponson-mounted 6 pounders (57mm), seven .30 caliber machine guns, and had armor ranging from .236 inches (6 mm) to .63 inches (16 mm). Designed for infantry support and for crossing trenches, it quickly became obsolete as its slow speed and light armor were soon superseded by other designs. The Mk. VIII was withdrawn from service in 1932.

American heavy tanks going into action at Souplet, France on the morning of 17 October 1918. Note the U.S. flag flying from the nearest vehicle. (National Archives)

In the lead-up to WW2, American heavy tank design continued to be focused on infantry support. The initial 1940 T1 design sported 4 turrets and bristled with machine guns. Its armament consisted of two primary turrets with low-velocity 75mm guns that had limited firing arcs, and two 360-degree rotating secondary turrets, one with a 20 mm gun and one with a 37mm gun, both fitted with coaxial .30 caliber machine guns. Two additional ball-mounted .30 machine guns were positioned in the rear corners, and two more .30 caliber MGs were to be fitted to the front for use by the driver firing forward.

In October 1940, a new design was finalized, reverting to a single turret. Designated the T1E2, which went into production as the M6 with a 3-inch (76mm) M7 gun, paired with a co-axial 37mm gun, the same model as in the M3 General Stuart Light Tank.  This was the heavy tank model that featured heavily in home front propaganda work, including many car-crushing demonstrations. Intended to be part of a triumvirate of armor, the heavy tank’s role was to break through enemy defenses; light tanks would handle reconnaissance and screening, and medium tanks were for exploiting breakthroughs. Enemy tank destruction was not an original mission for heavy tanks; the US built specialized tank destroyers for that mission.

T1E2 prototype

At twice the weight of medium tanks, the M6 was deemed too heavy for transport and was primarily relegated to home front duties. American Army doctrine, which stressed mobility and exploitation, left little role for the heavy tank, which was deemed too slow for the mobile operations envisioned (and were put into practice in the autumn of 1944 in Northwest Europe). It became clear that the 3-inch gun was insufficient armament for a heavy tank, as medium tanks were sporting equivalent or heavier calibers, and that the co-axial 37mm was redundant. A 90mm cannon was substituted and paired with a co-axial .30 caliber machine gun. Before this model could be put into production, Eisenhower nixed the heavy tank project, declaring the vehicles unnecessary and unwanted. The M6 was declared obsolete on December 14, 1944, on the eve of the Battle of the Bulge.

However, increasing encounters with German heavy armor during the vicious Battle of the Bulge, where American armor came off second best, and American troops’ arrival at the heavily fortified German border soon revived interest in the heavy tank. Additional frontal armor and a larger caliber main gun were incorporated into the next heavy tank designs. A modified T1 to be fitted with a 105mm gun and the non-turreted T28 were prototyped but did not see wartime service.  Field modifications to the ubiquitous M4 Sherman medium tank and factory-produced Jumbo models filled the gap. Despite uneven exchanges with German armor and the failure of the specialized tank destroyer doctrine, American medium tanks were deemed adequate for concluding the war.

An American M26 Pershing heavy tank engages a German Panther in the center of the city of Cologne. (National Archives)

Still, a “heavy” tank did see combat in the waning days of WWII. Designed as a successor to the M4 Sherman medium tank, the M26 Pershing was actually intended to be a medium tank, but it was re-designated a heavy tank and produced with heavier armor than originally intended. Armed with a 90mm gun, 20 Pershings saw action with the 3rd and 9th Armored Divisions of Bradley’s 1st Army. Twelve other Pershings were on ships destined for Okinawa in the Pacific but were delayed and arrived after combat operations ended. The Pershing was, however, deemed a success in combating German heavy armor during its limited service and encouraged continued research into heavy tank development.

The deployment of Soviet heavy tanks kept the US heavy tank design program alive postwar. The T43 program culminated in the 120mm-armed M103, but those wound up equipping only a single US Army armored battalion in Europe and three US Marine tank companies.

Heavy tanks were logistically a challenge to support in the field and difficult to justify economically in peacetime because they required different parts and maintenance. Supporting a single model of tank was easier for most armies, so the heavy tank was supplanted by the multi-role main battle tank. In 1960, the US army finally retired the heavy tank, replacing it with the M60.

M1A1 Abrams Main Battle Tank (MBT) provides heavy fire support in Operation AL FAJR. (DOD; Lance Cpl. J.A. Chaverri)

However, without purpose-built heavy armor, tank crews who came under fire improvised additional armor by placing spare track links, sandbags or even concrete to improve protection. In recent years, everything from additional reactive armor to full factory upgrades, such as the heavy armor (HA) addition of depleted uranium armor mesh to the original M1 Abrams, showed that protection from evolving weaponry and tactics was still needed. More recently, the TUSK (Tank Urban Survivability Kit) field installable kit for the M1 includes weaponry enhancement and applique reactive armor tiles to improve defenses against the common RPGs and other shaped-charged weapons encountered in Iraq.

Beloved by armor crews under fire but disliked by logistics and procurement departments during peacetime, the heavy tank’s ability to deal with and survive battlefield threats is needed more than ever, and the heavy tank still lives, though none are in production: heavy tanks are present in the form of these main battle tanks with factory and field enhancements for armor protection.

Key Statistics of Production US Heavy and Main Battle Tanks

About the Author
Tim Tow has studied the history of military intelligence and writes on technology and military affairs.

Sources

Hunnicutt Firepower: A History of the American Heavy Tank. Presidio Books: Novato, CA., 1988.

Hunnicutt Pershing: A History of the Medium Tank T20 Series. Presidio Books: Novato, CA., 1971.

Hunnicutt Patton: A History of the American Main Battle Tank. Presidio Books: Novato, CA., 1984.

Hunnicutt Abrams: A History of the American Main Battle Tank. Presidio Books: Novato, CA., 1990.

Zaloga, Steven. Armored Thunderbolt: The U.S. Army Sherman in World War II