M4 Sherman

The Medium Tank M4 was the main tank designed and built by the United States for allied forces in World War II, totaling roughly 50,000 tanks plus thousands more derivative vehicles under different model numbers with different abilities. In the United Kingdom lend-lease M4s were dubbed General Sherman after Union General William Tecumseh Sherman, continuing a practice of naming American tanks after famous Generals. The British name became popular in the US and the two names are often combined into M4 Sherman or shortened to Sherman. After WWII, Shermans served the US (in the Korean War) and many other nations world-wide and saw combat in many wars in the late 20th century.

The M4 was the sucessor to the Medium Tank M3. The M3 design had been influenced by the need to bring it into production as soon as possible for British use where it was known as "Lee" or "Grant". As a result the main gun was not in a turret but mounted asymmetrically in the hull which restricted its usefulness. The M4 corrected this shortcoming.

The U.S. Army Ordnance Department designed the M4 medium tank with a 75 mm gun in a traversing turret using the same chassis as the interim M3. During the production period, the U.S. Army's seven main sub-designations, M4, M4A1, M4A2, M4A3, M4A4, M4A5, and M4A6, did not necessarily indicate linear improvement: for example, A4 is not meant to indicate 'better than' A3. Instead, these sub-types indicated standardized production variations, which were in fact often manufactured concurrently at different locations. The sub-types differed mainly in terms of engine, although M4A1 differed from M4 by its fully cast upper hull rather than by engine; M4A4 had a longer engine system that also required a longer hull, longer suspension system, and more track blocks; M4A5 was an administrative placeholder for Canadian production; and M4A6 also elongated the chassis but totaled fewer than 100 tanks. Only the M4A2 and M4A6 were diesel while most Shermans were gasoline. "M4" might refer specifically to the single sub-type with its Continental radial engine or generically to the entire family of seven Sherman sub-types, depending on context. Many details of production, shape, strength, and performance improved throughout production life without an "advance" to the tank's basic model number; more durable suspension units, safer "wet" (W) ammunition stowage, and stronger armor arrangements such as the M4 Composite which had a cast front hull section mated to a welded rear hull. Note that the British nomenclature differed from that employed by the U.S.

Early Shermans mounted a 75 mm medium-velocity general-purpose gun. Later M4A1, M4A2, and M4A3 models received the larger T23 turret with a high-velocity 76 mm gun M1, which traded reduced HE and smoke performance for improved anti-tank performance. The British offered the QF 17 pounder (76.2 mm) anti-tank gun with its significant armour penetration but a significant initial (later rectified) HE shortcoming to the Americans but the US Ordnance Department was working on a 90 mm tank gun and declined. Later M4 and M4A3 were factory-produced with a 105 mm howitzer and a new distinctive mantlet in the original turret. The first standard-production 76mm-gun Sherman was an M4A1 accepted in January 1944 and the first standard-production 105mm-howitzer Sherman was an M4 accepted in February 1944.
M4 with 105 mm howitzer and a dozer blade, note the square-edged, welded, upper-hull plates found on most Shermans.
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M4 with 105 mm howitzer and a dozer blade, note the square-edged, welded, upper-hull plates found on most Shermans.

The US accepted in June-July 1944 a limited run of 254 M4A3E2 Jumbo Shermans with very thick armor and the 75 mm gun in a new heavier T23-style turret in order to assault fortifications. The M4A3 was the first to be factory-produced with the new HVSS suspension with wider tracks for lower ground pressure and the smooth ride of the HVSS with its experimental E8 designation led to the nickname Easy Eight for Shermans so equipped. The US developed a wide array of special attachments for the Sherman; few saw combat and most remained experimental but those which saw action included the bulldozer blade for Sherman dozer tanks, Duplex Drive for "swimming" Sherman tanks, R3 flame thrower for Zippo flame tanks, and the T34 60-tube 4.5 inch Calliope rocket launcher for the Sherman turret.

The M4 Sherman's basic chassis further undertook all the sundry roles of a modern, mechanized force, totaling roughly 50,000 Sherman tanks plus thousands more derivative vehicles under different model numbers including M32 and M74 "tow truck"-style recovery tanks with winches, booms, and most with an 81 mm mortar for smoke screens, M34 (from M32B1) and M35 (from M10A1) artillery prime movers, M7B1, M12, M40, and M43 self-propelled artillery, and upgunned M10 and M36 tank destroyers. As part of the deception plan of Operation Fortitude that drew German attention to the Pas de Calais rather than Normandy, inflatable rubber Shermans were manufactured and deployed across fields in Kent alongside plywood artillery pieces, another vesion of dummy Sherman was made from painted canvas over a steel frame and could be built over a Jeep and driven to simulate a moving tank.

During World War II, the M4 Sherman served with the US Army and US Marine Corps. US service history accommodated the large transfer of US Shermans to the allied forces of the United Kingdom (including Commonwealth), Soviet Union, Free French government-in-exile, Polish government-in-exile, Brazil, and China.

The US Marine Corps used the diesel M4A2 and gasoline-powered M4A3 in the Pacific. The US Army Tank Destroyer Command used the diesel M10 tank destroyer (based on the M4A2 chassis) in all theatres. However, the US Army Chief of the Armored Force Lt. Gen. Jacob L. Devers ordered that no diesel-engined Sherman tanks be used outside the Zone of Interior (ZI). The US Army used all types for either training or testing within the United States but intended the M4A2 and M4A4 to be the primary Lend-Lease exports. British needs also claimed a large share of the M4 and M4A1.
Last type in US service: M4A3E8(76)W Sherman used as artillery position during the Korean War
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Last type in US service: M4A3E8(76)W Sherman used as artillery position during the Korean War

The first US Shermans in combat were M4A1 used for Operation Torch in November 1942, shortly after the first M4A1 Shermans saw battle with the British 8th Army at the Second Battle of El Alamein in October 1942. Additional M4 and M4A1s replaced M3 Lees in US tank battalions over the course of the North African campaigns. The M4 and M4A1 were the main types in US units until late 1944, when the preferred M4A3 with its more powerful 500 hp engine began replacing M4s and M4A1s as the main US version. However, older M4s and M4A1s continued in US service for the rest of the war.

The first 76 mm gun Sherman to enter combat in July 1944 was the M4A1, closely followed by the M4A3. By the end of the war, half the US Army Shermans in Europe had the 76 mm gun for better anti-armor work while half had the 75 mm gun for better HE and smoke work, and some units intentionally kept a mix of both guns. The first HVSS Sherman to see combat was the M4A3E8(76)W in December 1944.

After WWII, the US kept the M4A3E8 "Easy Eight" in service with either 76 mm gun or 105 mm howitzer. The Sherman remained a common US tank in the 1950-1953 Korean War but the Army replaced Shermans with Patton tanks over the 1950s. The US continued to transfer Shermans to allies which contributed to wide foreign use worldwide.

Preface: Doctrine
A cutaway showing the internal arrangement of a M4A4 sherman.
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A cutaway showing the internal arrangement of a M4A4 sherman.

Stephen Ambrose states in Citizen Soldiers that, in accordance with U.S. Army doctrine at the time, the tank was designed to help infantry exploit a breakout rather than to engage in armor vs. armor combat. In defense, Allied armies deployed infantry anti-tank guns, tank destroyers, artillery fire and airpower to wear down the German armor before launching an armored counter-attack. In armored offense, American commanders were able to bring overwhelming numbers and airpower to bear.

The United States Army was influenced by the perceived actions of German tanks in the 1939 Polish Campaign. The popular conception in the US was that tanks had been used boldly as part of a new system of war called Blitzkrieg. According to US doctrine the role of defeating German armour fell to tank destroyers such as the M10 Wolverine rather than the medium tanks.

Although the US Combined Arms team included exceptional close air support, artillery, and engineer components, the tank component was weakened by the Tank Destroyer concept. This is most closely identified with the Chief of Army Ground Forces, General Leslie McNair who believed towed 57 mm AT guns, hand-held Bazookas and thinly armoured Tank Destroyers to be superior to friendly tanks for fighting enemy tanks. Under this doctrine, tanks were supposed to avoid tank-vs-tank combat as much as possible, leaving enemy tanks to the tank destroyers. In actual combat, McNair's doctrine led to US tanks having weaker guns and less armor protection than their German counterparts, and in the narrow confines of much of the terrain in Normandy, they could not avoid one-on-one encounters with German tanks.

Armament
Sherman armed with 105 mm howitzer.
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Sherman armed with 105 mm howitzer.

Early models are often criticized for the 75 mm gun chosen by the artillery branch of the US Army, which was not even specifically intended for anti-tank work. When it first saw combat in 1942, the Sherman's 75 mm gun, inherited from the M3 Lee, could kill the German tanks it faced in North Africa at normal combat ranges. The problem was the failure to upgrade tank guns to keep pace with the heavier German tanks being introduced later in the war. By the Normandy landings of 1944, the Sherman was ineffective against the medium Panther and heavy Tiger I tanks, against which the Sherman's 75 mm gun could not achieve a frontal penetration at any range. Even if it was outmoded for anti-tank use later in the war, the 75 mm gun was a solid weapon against infantry and other targets. In 1944-45, Shermans with 105 mm howitzers provided even more powerful high-explosive armament.
This M4A2(76) HVSS shows the T23 turret with later 76 mm gun's muzzle brake.
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This M4A2(76) HVSS shows the T23 turret with later 76 mm gun's muzzle brake.

Beginning in 1944, some Shermans mounted the higher-velocity 76 mm M1 gun giving them anti-tank firepower comparable to the Soviet T-34/85 and many of the AFVs it encountered, particularly the Pz IV, and StuG vehicles. The 76 mm armed vehicles first saw combat in Normandy, where half of the German tanks encountered were 45-ton Panthers. With a regular APCBC (Armour Piercing Capped, Ballistic Capped) ammunition, the 76 mm could reliably knock out a Panther only with a shot to its flank. Firing later HVAP ammunition, the 76 mm could penetrate the frontal armor of the Panther, but this ammunition was usually in short supply. By the end of the war, 50% of Sherman tanks were equipped with the superior 76 mm gun. The 75 mm gun remained better for HE and smoke, so most tank battalions intentionally kept some 75 mm armed Shermans to fulfil the role of smoke layer.
A USMC M4A3R3 uses its flame thrower armament during the Battle of Iwo Jima.
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A USMC M4A3R3 uses its flame thrower armament during the Battle of Iwo Jima.

In the relatively few Pacific tank battles, even the 75 mm gun Shermans outclassed the Japanese in every engagement. The use of HE (High Explosive) ammunition was preferred because anti-tank rounds punched cleanly through the thin armor of the Japanese tanks (light tanks of 1930s era design) without necessarily stopping them. Although the high-velocity guns of the tank destroyers were useful for penetrating fortifications, Shermans armed with flame throwers also destroyed Japanese fortifications. There was a variety of types of flame throwers, differing primarily in the type and location of launcher (and the US used similar devices on other tanks and LVTs, and also used flame-throwing Shermans in Europe).

Armor

The Sherman was designed to withstand a 37mm anti-tank gun, but by the end of the war, it was facing the high-velocity 75mm guns of the German Panther and Panzer IV and even the 88mm KwK43 L/71 of the King Tiger. The Sherman had armor protection comparable to other medium tanks of 1942. By 1944, this was no longer adequate. While Shermans were able to take on the Panzer III medium tanks in the North African campaigns, they were unable to withstand the weapons mounted on late-model Panzer IV, and Panther and Tiger tanks encountered in Italy and Normandy. Armor was more evenly distributed and thicker at the side than the PzIV; the top armor was equal to that of the Tiger.
This early 75 mm gun turret shows the single hatch.
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This early 75 mm gun turret shows the single hatch.

One concern was that if the main turret gun came to rest at the wrong angle it blocked one or the other of the two front hatches from being opened, thus potentially trapping the crew member inside. Eyewitness accounts have recorded the horror of hearing the screaming of the man trapped inside while he burned to death, and being helpless to rescue him. This was a common flaw in many WW2 tanks, including the British Cromwell, German Panzer IV, and German Tiger I. The M4 and T-34 had an escape hatch on the hull bottom to help minimize this problem, but it was not a complete solution, particularly if a crewman was wounded. The Army considered a greater concern to be the single hatch in the 3-man turret so Ordnance added a loader's hatch beside the commander's.
The 1943 modernization program for older tanks welded raised patches of applique armor to the sides of the turret and hull. Note also the "Rhino" Culin cutter on the bottom front, a field improvisation to break through the thick hedgerows of the Normandy bocage.
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The 1943 modernization program for older tanks welded raised patches of applique armor to the sides of the turret and hull. Note also the "Rhino" Culin cutter on the bottom front, a field improvisation to break through the thick hedgerows of the Normandy bocage.

Early Sherman models were prone to burning at the first hit. The Sherman gained grim nicknames like 'Tommycooker', after a World War I portable stove, or "Ronsons", after the cigarette lighter with the slogan "Lights up the first time, every time!" This vulnerability increased crew casualties and meant that damaged vehicles were less likely to be repairable. US Army research proved that the major reason for this was the use of unprotected ammo stowage in sponsons above the tracks. The common myth that the use of gasoline (petrol) engines was a culprit is unsupported; most WW2 tanks used gasoline engines and petrol was unlikely to ignite when hit with AP shells. Further, the diesel-engined M4A2 used by the Marines were considered to be much less prone to burn and explode than the diesel Soviet T-34.[1] At first a partial remedy to ammunition fire was found by welding one-inch thick applique armour plates to the vertical sponson sides over the ammunition stowage bins. Later models moved ammunition stowage to the hull floor, with additional water jackets surrounding the main gun ammunition stowage. This decreased the likelihood of "brewing up".
M4A3E2 Sherman Jumbo: Some units replaced the original 75 mm gun with a 76 mm gun.
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M4A3E2 Sherman Jumbo: Some units replaced the original 75 mm gun with a 76 mm gun.

Progressively thicker armour was added to hull front and turret mantlet in various improved models, while field improvisations included placing sandbags, spare track links, or even logs for increased protection against shaped-charge rounds. General George S. Patton, informed by his technical experts that the standoff produced by sandbags actually increased vulnerability to shaped-charge weapons (a controversial opinion) and that the machines' chassis suffered from the extra weight, forbade the use of sandbags and instead ordered tanks under his command to have the front hull welded with extra armour plates, salvaged from knocked-out American and German tanks. Approximately 36 of these up-armored Shermans were supplied to each of the armored divisions of the Third Army in the spring of 1945.

The (rare) M4A3E2 Sherman Jumbo variant had thicker frontal armor than the Tiger and Panther. Intended for the assault to breakout of the Normandy bridgehead, it entered combat in August 1944.

Mobility

Strategic Mobility

The U.S. Army required the Sherman not to exceed certain widths and weights so that the tank could use a wide variety of bridge, road, and rail travel for strategic, industrial, logistical, and tactical flexibility. Eisenhower demanded an improved tank from Army Chief of Staff George C. Marshall, who explained that he couldn't move a larger tank along the rail tracks to the East coast for shipping to Europe. The comparatively compact size of the Sherman also made it suited for transportation across the Atlantic and for amphibious operations. According to Ambrose, General George C. Marshall favored the M4 because two Shermans could be loaded on to an LST while only one larger tank could be accommodated.

Operational Mobility

Spares were readily available, an important consideration when more tanks were lost to mechanical failure than any other cause, including enemy action. Jim Dunnigan, a military analyst and war game designer, states that the number of tanks lost to mechanical failure in American, Soviet, and German armies in World War Two was in the ratio of one to five to ten. This is a striking testimony to the performance of the Sherman and highlights the relative mechanical unreliability of German tanks such as bedeviled the Tiger. The spectacular Allied mobility of 1944-45 could not have been achieved with tanks as unreliable as the Tiger or Panther, nor could the spectacular German mobility of 1939-41.

Tactical Mobility

The Sherman had good speed both on and off-road for the era. Off-road performance varied. In the desert, the Sherman's rubber tracks performed well. In the confined, hilly terrain of Italy, the Sherman could often cross terrain German tanks could not. However, US crews found that on soft ground, such as mud or snow, the narrow tracks gave poor floatation compared to wide-tracked second-generation German tanks such as the Panther. Soviet experiences were similar and tracks were modified to give grip in the snow. The US Army issued extended end connectors or 'duckbills' to add width to the standard tracks as a stopgap solution. Duckbills were original factory equipment for the heavy M4A3E2 Jumbo to compensate for the extra armor weight. The M4A3E8 'Easy Eight' Shermans and other late models with wider-tracked HVSS suspension corrected these problems, but formed only a small proportion of all tanks in service even in 1945.

Summary

The Sherman tank was comparatively fast and maneuverable, mechanically reliable, easy to manufacture and service, and produced in many special-purpose variants, whose capabilities differed greatly. It was effective in the infantry support role.

The Sherman performed well against WWII Japanese tanks, Italian tanks, and the German standard tank of WWII, the Panzer IV medium series. However, the typical Sherman was inferior in both armor and armament to the German Tiger heavy tanks and Panther "medium" (heavy by US standards), which was the most widely used German tank at the Western Front: about 50% of all German tanks there were Panthers. Whereas Panthers had been the more serious threat to the allied tanks, Tigers had a bigger psychological effect on Sherman crews, causing a "Tiger hysteria". Shermans would sometimes evade rather than confront Tigers, even if a tank only looked like one, such as the Panzer IV with turret skirts applied. In the Normandy campaign, it could take four to five Shermans to knock out a single Tiger tank by maneuvering to its weaker flank or rear armor; the Soviet T-34s fared similarly against the German tanks, as had the German PzIII earlier against the Soviet heavy tanks. After Normandy, increasing numbers of upgunned Shermans with better ammunition reduced the imbalance against the heavier German tanks. Because there were relatively few Tigers, they could be defeated by weight of numbers or superior tactics, using upgunned Shermans working with tank destroyers such as the M36 Jackson (with a 90 mm anti-tank gun) and the M18 Hellcat (a mobile, fast tracked vehicle with the same 76 mm gun). Skilled US Sherman crews and commanders, such as Lieutenant Colonel Creighton Abrams or Sergeant Lafayette Poole, were able to knock out dozens of German tanks each.

The majority of losses of Shermans were not in battle with other tanks, but from mines, aircraft, infantry anti-tank weapons and, on occasion, friendly fire. This should not be surprising considering that the entire strategy of blitzkrieg, as practiced first by the Germans and later by the Allies, was to strike the enemy where they are weakest and wreak havoc in their rear areas, rather than attempting brute-force frontal attacks. A noted exception would be Battle of Kursk where frontal attack might fared better. Thus, although their tanks were less powerful, this turned out to be as irrelevant to the outcome of the final half of World War Two as the French and Russian superiority in tank forces was in the first half. US armoured forces ultimately triumphed over their German counterparts because of numerical superiority, a more consistent supply of fuel and ammunition, and the allied air superiority at Normandy, with aircraft being the biggest danger to tanks.

According to Belton Y. Cooper's memoir of his 3rd Armored Division service, the Shermans were "death traps"; the overall combat losses of the division were extremely high. The unit was nominally assigned by table of organization 232 medium tanks (including 10 M26 Pershing tanks that made it into combat). 648 tanks were totally destroyed in combat, and a further 1,100 needed repair, of which nearly 700 were as a result of combat. According to Cooper, the 3rd Armored therefore lost 1,348 medium tanks in combat, a loss rate of over 580%. Cooper was the junior officer placed in charge of retrieving damaged and destroyed tanks. As such, he had an intimate knowledge of the actual numbers of tanks damaged and destroyed, the types of damage they sustained, and the kinds of repairs that were made. His figures are comparable to those given in the Operational History of 12th U.S. Army Group: Ordnance Section Annex.

The disparity in quality is not only highlighted in statistics taken over entire campaigns; in a single battle, The British Columbia Regiment had nearly 100 percent vehicle casualties at Point 195 in Normandy during August 1944. Operating in darkness, the regiment navigated to the wrong hill and found itself surrounded by German armoured units on adjacent hilltops and subsequently wiped out during the next morning's fighting.[1]

The only other Second World War tank produced in comparable numbers to the Sherman was the Soviet T-34 series, which many critics consider as a contender for best tank of World War II, although it too had high losses during the war. Compared to the M4 Sherman, the T-34 had lower ground pressure and sloped side armor while the M4's advantages included much better ergonomics and (on late models) fire-resistant "wet" ammunition stowage. Each was a general-purpose medium design that served as the main tank of its respective country in WWII, was upgraded, served into the Cold War, and outfitted allies. During the Korean War, US Shermans performed well against their T-34-85 adversaries, although this probably should be attributed to the disparity in Crew quality, rather than to technical superiority.

Replacement

Almost immediately after the M4 Sherman was standardised, the US Ordnance Department started work on a successor. Starting with the T20, the Ordnance Department developed a series of improved medium tank prototypes cumulating with the T23E3 in 1943. The T23E3 featured a lower silhouette, increased armour and greater firepower than the M4 (making it comparable with the Russian T34/85, if not the German Panther) and could have been available in time for D-Day. Yet despite the design being standardised as the M27 it was never mass produced. The reason for this lay partly in the failure of the Army Ground Forces command (AGF) to recognise the growing obsolesence of the M4 design. The Sherman had performed admirably in North Africa and Italy so there was no sense of urgency to replace it. However, German Tigers and Panthers had already been encountered so the writing was clearly on the wall for the basic Sherman design and the decision of the AGF that they were satisfied with their current equipment seems surprisingly short-sighted.

Officially, the AGF declined to adopt the M27 as they did not wish to interrupt M4 production, although by 1943 the manufacture of M4's had reached such a mammoth scale it seems unlikely that a staged switch over to M27 production would have significantly reduced tank output. Perhaps more importantly the M27 would have mounted the 76 mm gun, the introduction of which to the tank force was resisted by the AGF. The Ordnance Department would later suffer almost equal difficulty convincing the AGF to accept the upgunned versions of the Sherman with the net result that not a single 76 mm armed Sherman was in service in time for D-Day, even though they could have been available months earlier. The AGF's stock reason for rejecting the 76 mm gun was that it would encourage tank crews to stalk enemy tanks, obviously an idea in conflict with then current US armour doctrine. However US tanks would not always be able to avoid direct confrontations with German tanks. Interestingly, many features of the M27 would eventually be incorporated into the improved M4 variants, most notably a modified version of the M27 turret was used for the 76 mm gun armed Shermans.

With the M27 rejected, the Ordnance Department continued designing larger tanks armed with 90 mm guns, ultimately developing the T26E3. Once again the Ordnance Department resisted the adoption of this design despite the fact that Sherman tanks were regularly taking a beating from the newer German Panzers in Normandy. However, after the Ardennes campaign highlighted the shortcomings of the M4 design the European Theatre of Operations High Command intervened, stating they had no further requirement for tanks armed with 75 mm and 76 mm guns and instead wanted only tanks armed with 90 mm and 105 mm guns. This intervention resulted in the T26E3 ultimately being standardised as the M26 Pershing and accepted into service, but with the war in its final stages the Sherman remained comfortably the most important Allied tank on the Western Front for the rest of the war.