M4 Sherman


The M4 Sherman, officially Medium Tank, M4, was the most widely used medium tank by the United States and Western Allies in World War II. The M4 Sherman proved to be reliable, relatively cheap to produce, and available in great numbers. It was also the basis of several successful tank destroyers, such as the M10, Achilles and M36. Tens of thousands were distributed through the Lend-Lease program to the British Commonwealth and Soviet Union. The tank was named by the British for the American Civil War general William Tecumseh Sherman.
The M4 Sherman evolved from the M3 Medium Tank, which had its main armament in a side sponson mount. The M4 retained much of the previous mechanical design, but moved the main 75 mm gun into a fully traversing central turret. One feature, a one-axis gyrostabilizer, was not precise enough to allow firing when moving but did help keep the reticle on target, so that when the tank did stop to fire, the gun would be aimed in roughly the right direction. The designers stressed mechanical reliability, ease of production and maintenance, durability, standardization of parts and ammunition in a limited number of variants, and moderate size and weight. These factors, combined with the Sherman's then-superior armor and armament, outclassed German light and medium tanks fielded in 1939–42. The M4 went on to be produced in large numbers, being the most produced tank in American history: The Soviets' T-34 medium tank was the only tank design produced in larger numbers during World War II. The Sherman spearheaded many offensives by the Western Allies after 1942.
When the M4 tank went into combat in North Africa with the British Army at El Alamein in late 1942, it increased the advantage of Allied armor over Axis armor and was superior to the lighter German and Italian tank designs. For this reason, the US Army believed that the M4 would be adequate to win the war, and relatively little pressure was initially exerted for further tank development. Logistical and transport restrictions, such as limitations imposed by roads, ports, and bridges, also complicated the introduction of a more capable but heavier tank. Tank destroyer battalions using vehicles built on the M4 hull and chassis, but with open-topped turrets and more potent high-velocity guns, also entered widespread use in the Allied armies. Even by 1944, most M4 Shermans kept their dual-purpose 75 mm gun. By then, the M4 was inferior in firepower and armor to increasing numbers of German heavy tanks, but was able to fight on with the help of considerable numerical superiority, greater mechanical reliability, better logistical support, and support from growing numbers of fighter-bombers and artillery pieces. Some Shermans were produced with a more capable gun, the 76 mm gun M1, or refitted with a 76.2mm calibre Ordnance QF 17-pounder gun by the British.
The relative ease of production allowed large numbers of the M4 to be manufactured, and significant investment in tank recovery and repair units allowed disabled vehicles to be repaired and returned to service quickly. These factors combined to give the Allies numerical superiority in most battles, and many infantry divisions were provided with M4s and tank destroyers.
After World War II, the Sherman, particularly the many improved and upgraded versions, continued to see combat service in many conflicts around the world, including the UN forces in the Korean War, with Israel in the Arab–Israeli wars, briefly with South Vietnam in the Vietnam War, and on both sides of the Indo-Pakistani War of 1965.

U.S. design prototype

The U.S. Army Ordnance Department designed the M4 medium tank as a replacement for the M3 medium tank. The M3 was an up-gunned development of the M2 Medium Tank of 1939, in turn derived from the M2 light tank of 1935. The M3 was developed as a stopgap measure until a new turret mounting a 75 mm gun could be devised. While it was a big improvement when tried by the British in Africa against early German tanks, the placement of a 37 mm gun turret on top gave it a very high profile, and the unusual side-sponson mounted main gun, with limited traverse, could not be aimed across the other side of the tank. Though reluctant to adopt British weapons into their arsenal, the American designers were prepared to accept proven British ideas. British ideas, as embodied in a tank designed by the Canadian General Staff, also influenced the development of the American Sherman tank. Before long American military agencies and designers had accumulated sufficient experience to forge ahead on several points. In the field of tank armament the American 75 mm and 76 mm dual-purpose tank guns won the acknowledgement of British tank experts. Detailed design characteristics for the M4 were submitted by the Ordnance Department on 31 August 1940, but development of a prototype was delayed while the final production designs of the M3 were finished and the M3 entered full-scale production. On 18 April 1941, the U.S. Armored Force Board chose the simplest of five designs. Known as the T6, the design was a modified M3 hull and chassis, carrying a newly designed turret mounting the M3's 75 mm gun. This would later become the Sherman.
The Sherman's reliability resulted from many features developed for U.S. light tanks during the 1930s, including vertical volute spring suspension, rubber-bushed tracks, and a rear-mounted radial engine with drive sprockets in front. The goals were to produce a fast, dependable medium tank able to support infantry, provide breakthrough striking capacity, and defeat any tank then in use by the Axis nations.
The T6 prototype was completed on 2 September 1941. The upper hull of the T6 was a single large casting. It featured a single overhead hatch for the driver, and a hatch in the side of the hull. In the later M4A1 production model, this large casting was maintained, although the side hatch was eliminated and a second overhead hatch was added for the assistant driver. The modified T6 was standardized as the M4, and production began in February 1942. The cast-hull models would later be re-standardized as M4A1, with the first welded-hull models receiving the designation M4. In August, 1942, a variant of the M4 was put forth by the Detroit Arsenal to have angled, rather than rounded hull and turret armor. The changes were intended to improve the tank's protection without increasing weight or degrading other technical characteristics.

Doctrine

As the United States approached entry into World War II, armored employment was doctrinally governed by Field Manual 100–5, Operations. That field manual stated:
The M4 was, therefore, not originally intended primarily as an infantry support tank. It placed tanks in the "striking echelon" of the armored division, and placed the infantry in the "support echelon", without directing that tanks should only seek to attack other tanks, thus leaving target selection up to the field commander based on what types of units were available to him to attack. A field manual covering the use of the Sherman described fighting enemy tanks when necessary as one of the many roles of the Sherman, but devoted only one page of text and four diagrams to tank-versus-tank action, out of 142 pages. This early armored doctrine was heavily influenced by the sweeping early war successes of German blitzkrieg tactics. By the time M4s reached combat in significant numbers, battlefield demands for infantry support and tank versus tank action far outnumbered the occasional opportunities of rear-echelon exploitation.
United States doctrine held that the most critical anti-tank work - stopping massed enemy tank attacks - was primarily to be done by towed and self-propelled anti-tank guns, operated by "Tank destroyer" battalions, with friendly tanks being used in support if possible. Speed was essential in order to bring the tank destroyers from the rear to destroy incoming tanks. This doctrine was rarely followed in combat, as it was found to be impractical. Commanders were reluctant to leave tank destroyers in reserve; if they were, it was also easier for an opposing armored force to achieve a breakthrough against an American tank battalion, which would not have all of its anti-tank weapons at the front during the beginning of any attack.

U.S. production history

The first production of the Sherman took place at the Lima Locomotive Works, with many early vehicles reserved for British use under Lend-Lease; the first production Sherman was given to the U.S. Army for evaluation, and the second tank of the British order went to London. Nicknamed Michael, probably after Michael Dewar, head of the British tank mission in the U.S., the tank was displayed in London and is now an exhibit at The Tank Museum, Bovington, UK.
In World War II, the U.S. Army ultimately fielded 16 armored divisions, along with 70 separate tank battalions, while the U.S. Marine Corps fielded six tank battalions. A third of all Army tank battalions, and all six Marine tank battalions, were deployed to the Pacific Theater of Operations. Prior to September 1942, President Franklin D. Roosevelt had announced a production program calling for 120,000 tanks for the Allied war effort. Although the American industrial complex was not affected by enemy aerial bombing or submarine warfare as was Japan, Germany and, to a lesser degree, Great Britain, an enormous amount of steel for tank production was diverted to the construction of warships and other naval vessels. Steel used in naval construction amounted to the equivalent of approximately 67,000 tanks; and consequently only about 53,500 tanks were produced during 1942 and 1943.
The Army had seven main sub-designations for M4 variants during production: M4, M4A1, M4A2, M4A3, M4A4, M4A5, and M4A6. These designations did not necessarily indicate linear improvement; in that "M4A4" did not indicate it was better than "M4A3". These sub-types indicated standardized production variations, which were in fact often manufactured concurrently at different locations. The sub-types differed mainly in engines, although the M4A1 differed from the other variants by its fully cast upper hull, with a distinctive rounded appearance. The M4A4 had a longer engine that required a longer hull and more track blocks, and thus the most distinguishing feature of the M4A4 was the wider longitudinal spacing between the bogies. "M4A5" was an administrative placeholder designation for Canadian production. The M4A6 had a radial diesel engine as well as the elongated chassis of the M4A4, but only 75 of these were ever produced.
Most Sherman sub-types ran on gasoline. The air-cooled Continental-produced Wright R975 Whirlwind 9 cylinder radial gasoline engine in the M4 and M4A1 produced. The M4A3 used the liquid-cooled Ford GAA V8 gasoline engine, and the M4A4 used the liquid cooled 30 cylinder Chrysler A57 multibank gasoline engine. There were also two diesel engined variants. The M4A2 was powered by a pair of liquid cooled GMC 6–71 two-stroke inline engines, that produced a total of, while the M4A6 used an RD-1820 that produced. A 24-volt electrical system was used in the M4. The M4A2 and M4A4 were mostly supplied to other Allied countries under Lend-Lease. The term "M4" can refer specifically to the initial 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 while in production, without a change to the tank's basic model number. These included stronger suspension units, safer "wet" ammunition stowage, and stronger or more effective armor arrangements, such as the M4 "Composite", which had a cheaper to produce cast front hull section mated to a regular welded rear hull. British nomenclature regarding Sherman variants differed from that employed by the U.S.
Early Shermans mounted a 75 mm medium-velocity general-purpose gun. Although Ordnance began work on the T20 medium tank series as Sherman replacements, ultimately the Army decided to minimize production disruption by incorporating elements of the design into the Sherman. Later M4A1, M4A2, and M4A3 models received a larger turret with a high-velocity 76 mm gun from the T23 tank. The first standard-production 76 mm gun-armed Sherman was an M4A1, accepted in January 1944, which first saw combat in July 1944 during Operation Cobra. Variants of the M4 and M4A3 were factory-produced with a 105 mm howitzer and a distinctive rounded mantlet, which surrounded the main gun, on the turret. The first Sherman variant to be armed with the 105 mm howitzer was the M4, first accepted in February 1944.
From May to July 1944, the Army accepted a limited run of 254 M4A3E2 Jumbo Shermans, which had very thick hull armor and the 75 mm gun in a new, better- protected T23-style turret, in order to assault fortifications. The M4A3 model was the first to be factory-produced with the horizontal volute spring suspension system with wider tracks to distribute weight, beginning in August 1944. With the smooth ride of the HVSS, it gained the nickname "Easy Eight" from its experimental "E8" designation. The M4 and M4A3 105 mm-armed tanks, as well as the M4A1 and M4A2 76 mm-armed tanks, were also eventually equipped with HVSS. Both the Americans and the British developed a wide array of special attachments for the Sherman, although few saw combat, remaining experimental. Those that saw action included a bulldozer blade, the Duplex Drive system, flamethrowers for Zippo flame tanks, and various rocket launchers such as the T34 Calliope. British variants formed part of the group of specialized vehicles collectively known as "Hobart's Funnies".
The M4 Sherman's basic chassis was used for all the sundry roles of a modern mechanized force. These included the M10 and M36 tank destroyers; M7B1, M12, M40, and M43 self-propelled artillery; the M32 and M74 "tow truck"-style recovery tanks with winches, booms, and an 81 mm mortar for smoke screens; and the M34 and M35 artillery prime movers.
DesignationManufacturersTotalDate
M4Pressed Steel Car Company
Baldwin Locomotive Works
American Locomotive Co.
Pullman-Standard Car Company
Detroit Tank Arsenal		6,748July 1942 – January 1944
M4Detroit Tank Arsenal800February 1944 – September 1944
M4 HVSSDetroit Tank Arsenal841September 1944 – March 1945
M4A1Lima Locomotive Works
Pressed Steel Car Company
Pacific Car and Foundry Company		6,281February 1942 – December 1943
M4A1WPressed Steel Car Company2,171January 1944 – December 1944
M4A1W HVSSPressed Steel Car Company1,255January 1945 – July 1945
M4A2Fisher Tank Arsenal

Pullman-Standard Car Company
American Locomotive Co.
Baldwin Locomotive Works
Federal Machine and Welder Co.		8,053April 1942 – May 1944
M4A2WFisher Tank Arsenal1,594May 1944 – December 1944
M4A2W HVSSFisher Tank Arsenal
Pressed Steel Car Company		1,321January 1945 – May 1945
M4A3Ford Motor Company1,690June 1942 – September 1943
M4A3WFisher Tank Arsenal2,420February 1944 – December 1944
M4A3W HVSSFisher Tank Arsenal651January 1945 – March 1945
M4A3E2Fisher Tank Arsenal254May 1944 – July 1944
M4A3WFisher Tank Arsenal
Detroit Tank Arsenal		1,925March 1944 – December 1944
M4A3W HVSSDetroit Tank Arsenal2,617August 1944 – April 1945
M4A3Detroit Tank Arsenal500May 1944 – September 1944
M4A3 HVSSDetroit Tank Arsenal2,539September 1944 – June 1945
M4A4Detroit Tank Arsenal7,499July 1942 – November 1943
M4A6Detroit Tank Arsenal75October 1943 – February 1944
Total49,234

Service history

Allocation

During World War II, approximately 19,247 Shermans were issued to the U.S. Army and about 1,114 to the U.S. Marine Corps. The U.S. also supplied 17,184 to Great Britain, while the Soviet Union received 4,102 and an estimated 812 were transferred to China. These numbers were distributed further to the respective countries' allied nations.
The U.S. Marine Corps used the diesel M4A2 and gasoline-powered M4A3 in the Pacific. However, the Chief of the Army's Armored Force, Lt. Gen. Jacob L. Devers, ordered that no diesel-engined Shermans be used by the Army outside the Zone of Interior. The 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.

First combat

Shermans were being issued in small numbers for familiarization to U.S. armored divisions when there was a turn of events in the Western Desert campaign. Axis forces had taken Tobruk and were advancing into Egypt and Britain's supply line through the Suez Canal was threatened. The US considered collecting all Shermans together so as to be able to send the 2nd Armored Division under Patton to reinforce Egypt, but delivering the Shermans directly to the British was quicker and over 300 – mostly M4A1s, but also including M4A2s – had arrived there by September 1942.
The Shermans were modified for desert warfare with sandshields over the tracks and other stowage. The Sherman first saw combat at the Second Battle of El Alamein in October 1942 with the British 8th Army. At the start of the offensive, there were 252 tanks fit for action. These equipped the British 9th Armoured Brigade, 2nd Armoured Brigade and 8th and 20th Armoured Brigades. Their first encounter with tanks was against German Panzer III and IV tanks with long 50 mm and 75 mm guns engaging them at. There were losses to both sides.
The first U.S. Shermans in battle were M4s and M4A1s in Operation Torch the following month. On 6 December, near Tebourba, Tunisia, a platoon from the 2nd Battalion, 13th Armored Regiment was lost to enemy tanks and anti-tank guns.
Additional M4s and M4A1s replaced M3s in U.S. tank battalions over the course of the North African campaign.
The M4 and M4A1 were the main types in U.S. units until the fall of 1944, when the Army began replacing them with the preferred M4A3 with its more powerful engine. Some M4s and M4A1s continued in U.S. service for the rest of the war. The first Sherman to enter combat with the 76 mm gun in July 1944 was the M4A1, closely followed by the M4A3. By the end of the war, roughly half the U.S. Army Shermans in Europe had the 76 mm gun. The first HVSS-equipped Sherman to see combat was the M4A3W in December 1944.

Eastern Front

Under Lend-Lease, 4,102 M4A2 medium tanks were sent to the Soviet Union. Of these, 2,007 were equipped with the original 75 mm main gun, with 2,095 mounting the more-capable 76 mm gun. The total number of Sherman tanks sent to the USSR under Lend-Lease represented 18.6% of all Lend-Lease Shermans. The first 76 mm-armed M4A2 Shermans started to arrive in Soviet Union in the late summer of 1944.
The Red Army considered the M4A2 to be much less prone to catch fire due to ammunition detonation than the T-34/76, but the M4A2 had a higher tendency to overturn in road accidents and collisions or because of rough terrain than the T-34 due to its higher center of gravity.
By 1945, some Red Army armoured units were equipped entirely with the Sherman. Such units included the 1st Guards Mechanized Corps, the 3rd Guards Mechanized Corps and the 9th Guards Mechanized Corps, amongst others. The Sherman was largely held in good regard and viewed positively by many Soviet tank crews, with compliments given to its reliability, ease of maintenance, generally good firepower and decent armour protection, as well as an auxiliary power unit to keep the tank's batteries charged without having to run the main engine, as was required on the T-34.

Pacific Theater

While combat in the European Theater of Operations often consisted of high-profile armored warfare, the mainly naval nature of the Pacific Theater of Operations relegated it to secondary status for both the Allies and the Japanese. While the U.S. Army fielded 16 armored divisions and 70 separate tank battalions during the war, only a third of the battalions and none of the divisions were deployed to the Pacific Theater. The Imperial Japanese Army deployed only their 2nd Tank Division to the Pacific during the war. Armor from both sides mostly operated in jungle terrain that was poorly suited to armored warfare. For this type of terrain, the Japanese and the Allies found light tanks easier to transport and employ.
During the early stages of combat in the Pacific, specifically the Guadalcanal Campaign, the U.S. Marine Corps' M2A4 light tank fought against the equally-matched Type 95 Ha-Go light tank; both were armed with a 37 mm main gun. However, the M2 was newer by five years. By 1943, the IJA still used the Type 95 and Type 97 Chi-Ha medium tanks, while Allied forces were quickly replacing their light tanks with 75 mm-armed M4s. The Chinese in India received 100 M4 Shermans and used them to great effect in the subsequent 1944 and 1945 offensives in the CBI Battlefield.
, an M4A1 advances through a tropical rain forest on New Britain, in the South-West Pacific
To counter the Sherman, the Japanese developed the Type 3 Chi-Nu and the heavier Type 4 Chi-To; both tanks were armed with 75 mm guns, albeit of different type. Only 166 Type 3s and two Type 4s were built, and none saw combat; they were saved for the defense of the Japanese home islands, leaving 1930s vintage light and medium armor to do battle against 1940s built Allied light and medium armor.
During the later years of the war, general purpose high explosive ammunition was preferred for fighting Japanese tanks because armor-piercing rounds, which had been designed for penetrating thicker steel, often went through the thin armor of the Type 95 Ha-Go and out the other side without stopping. Although the high-velocity guns of tank destroyers were useful for penetrating fortifications, M4s armed with flamethrowers were often deployed, as direct fire seldom destroyed Japanese fortifications.

Post–World War II

After World War II, the U.S. kept the M4A3E8 '"Easy Eight" in service, with either the 76 mm gun or a 105 mm M4 howitzer. The Sherman remained a common U.S. tank in the Korean War, where it fought alongside the M26 Pershing and M46 Patton. The M4A3W HVSS Sherman and T-34-85 were comparable and could destroy each other at normal combat ranges, although the use of High Velocity Armor Piercing ammunition, advanced optics, and better crew training gave the Sherman an advantage. The M4A3W HVSS Sherman, using 76 mm HVAP ammunition, destroyed 41 enemy tanks from July–November 1950. The lighter M4A3W HVSS tank became the preferred U.S. tank in the later phases of the war in Korea, due to the mechanical reliability of the M4, its ease of maintenance, and its driveability compared to the M26 tank.
The U.S. Army replaced the M4 in 1957. The U.S. continued to transfer Shermans to its allies, which contributed to widespread foreign use.
The Israeli Defense Force used Shermans from its creation in 1948 until the 1980s, having first acquired a single M4A2 lacking main armament from British forces as they withdrew from Israel. The popularity of the tank compared to the outdated, 1934-origin French Renault R35 interwar light tanks with their 37 mm short-barreled guns, which made up the bulk of the IDF's tank force, led to the purchase of 30 unarmed M4s from Italian scrapyards. Three of these, plus the original M4A2, saw extensive service in the 1948-9 war of independence. The remainder were then serviced and rearmed with 75 mm guns and components whenever these became available, composing a large part of Israeli tank forces for the next eight years. The 75 mm-armed Shermans were replaced by M4A1 Shermans imported from France before the 1956 Suez Crisis, after it was realised that their armor penetration was insufficient for combat against newer tanks such as the IDF Centurions as well as the T-34-85s being delivered to Egyptian forces. During further upgrades, the French military helped develop a conversion kit to upgrade about 300 Shermans to the long high-velocity 75 mm gun CN 75-50 used in the AMX-13. These were designated Sherman M-50 by the Israelis. Before the Six-Day War in 1967, the Israeli Army upgraded about 180 M4A1W HVSS Shermans with the French 105 mm Modèle F1 gun, re-engined them with Cummins diesel engines and designated the upgraded tank Sherman M-51. The Sherman tanks, fighting alongside the 105 mm Centurion Sh'ot Kal and M48 Patton tanks, were able to defeat the T-34/85, T-54/55/62 series, and IS-3 tanks used by the Egyptian and Syrian forces in the 1967 Six-Day War.
M4A3s were also used by British forces in Indonesia during the Indonesian National Revolution until 1946, when they were passed on to the KNIL, which used them until 1949 before they were passed on to the Indonesian Army.

Armament

Gun development

As the Sherman was being designed, provisions were made so that multiple types of main armament could be mounted in the turret. The possibility of mounting the main gun of the M6 heavy tank, the 3-inch gun M7, in the turret of the M4 Sherman was explored first, but its size and weight made it too large to fit in the turret of the Sherman. Development on a new 76 mm gun better-suited to the Sherman began in fall 1942.
In early 1942, tests began on the feasibility of mounting a 105 mm howitzer into the turret of the Sherman. The basic 105 mm howitzer M2A1 was found to be ill-designed for mounting in a tank turret, so it was completely redesigned and re-designated the 105 mm howitzer M4. After modifications to the turret and interior of the hull, the Ordnance Department expressed its approval of the project, and production of M4 tanks armed with 105 mm howitzers began in February 1944.
The Sherman would enter combat in 1942 equipped with the 75 mm gun M3, a 40-caliber gun that could penetrate of unsloped rolled homogeneous armor at and at firing the usual M61 round. Facing the early Panzer III and Panzer IV in North Africa, the Sherman's gun could penetrate the frontal armor of these tanks at normal combat ranges, within. U.S. Army Intelligence discounted the arrival of the Tiger I in 1942 and the Panther tank in 1943, predicting that the Panther would be a heavy tank like the Tiger I, and doubted that many would be produced. There were also reports of British QF 6 pdr guns being able to destroy the Tiger I. However, this only happened at very close ranges and against the thinner side armor. Due to their misconceptions related to this, and also due to tests that seemed to prove that the 76 mm gun was able to destroy both the Tiger and the Panther, the leadership of Army Ground Forces were not especially concerned by the Tiger I. The criteria and results of the 76 mm gun tests were later ruled to have been inaccurate when compared to real-world conditions, with Eisenhower even remarking that he was wrongly told by Ordnance that the 76 mm could knock out any German tank. The Army also failed to anticipate that the Germans would attempt to make the Panther the standard tank of their panzer divisions in 1944, supported by small numbers of Tiger I and IIs.
When the newly-designed 76 mm gun, known as the T1, was first installed in the M4 in spring 1943, it was found to unbalance the turret, and the gun barrel also protruded too far forward, making it more difficult to transport and susceptible to hitting the ground when the tank traveled over undulating terrain. The barrel length was reduced by , resulting in the M1 variant. Mounting this gun in the original M4 turret proved problematic, so the turret for the aborted T23 tank project was used instead for the definitive production version of the 76 mm M4 Shermans, along with a modified version of the gun known as the M1A1.
Despite the Ordnance Department's development of new 76 mm and 90 mm anti-tank guns, the Army Ground Forces rejected their deployment as unnecessary. An attempt to upgrade the M4 Sherman by installing the 90 mm-armed turret from the T26 tank project on an M4 hull in April 1944 was halted after realizing it could not go into production sooner than the T26 and would likely delay T26 development. Even in 1943, most German armored fighting vehicles mounted the 7.5 cm KwK 40. As a result, even weakly armored light German tank destroyers such as the Marder III, which was meant to be a stop-gap measure to fight Soviet tanks in 1942, could destroy Shermans from a distance. The disparity in firepower between the German armored fighting vehicles that began to be fielded in 1943 and the 75 mm-armed M4 was the impetus to begin production of 76 mm-armed M4s in January 1944. In testing prior to the invasion of Normandy, the 76 mm gun was found to have an undesirably large muzzle blast that kicked up dust from the ground and obscured vision for further firing. The M1A1C gun, which entered production lines in March 1944, was threaded for a muzzle brake, but as the brakes were still in development, the threads were protected with a cap. The addition of a muzzle brake on the new M1A2 gun beginning in October 1944 finally solved this problem by directing the blast sideways.
Army doctrine at the time emphasized the multirole ability of the tank, and the capability of the high explosive shell was considered important. Being a dedicated anti-tank gun, the 76 mm had a much weaker high explosive shell than the existing 75 mm, and was not initially accepted by various U.S. armored division commanders, even though many had already been produced and were available. All of the U.S. Army M4s deployed initially in Normandy in June 1944 had the 75 mm gun. Fighting against Panther tanks in Normandy quickly demonstrated the need for better anti-tank firepower, and the 76 mm M4s were deployed to First Army units in July 1944. Operation Cobra was the combat debut of the 76 mm gun-armed Sherman, in the form of the M4A1W. General George S. Patton's Third Army were initially issued 75 mm M4s and accepted 76 mm-armed M4s only after the Battle of Arracourt against Panther tanks in late September 1944.
The higher-velocity 76 mm gun gave Shermans anti-tank firepower at least equal to most of the German vehicles they encountered, particularly the Panzer IV and StuG III. The gun could penetrate of unsloped RHA at and at using the usual M62 round. The M1 helped to equalize the Sherman and the Panzer IV in terms of firepower; the 48-caliber 7.5 cm KwK 40 of the Panzer IV could penetrate of unsloped RHA at and at. The 76 mm gun was still inferior to the much more powerful 70-caliber 7.5 cm KwK 42 of the Panther, which could penetrate of unsloped RHA at and at using the usual PzGr.39/42 round. The 76 mm was capable of knocking out a Panther at normal combat ranges from the flanks or rear, but could not overcome the glacis plate. Due to its 55 degree slope, the Panther's glacis had a line of sight thickness of with actual effectiveness being even greater. An M4 might only knock out a Panther frontally from point-blank range by aiming for its turret front and transverse-cylindrical shaped mantlet, the lower edge of which on most Panthers constituted a vulnerable shot trap. A 76 mm-armed Sherman could penetrate the upper frontal hull superstructure of a Tiger I tank from normal combat ranges. Although the new gun lessened the gap between the two tanks, the Tiger I was still capable of knocking an M4 out frontally from over.
In late summer 1944, after breaking out of the bocage and moving into open country, U.S. tank units that engaged German defensive positions at longer ranges sometimes took 50% casualties before spotting where the fire was coming from. The average combat range noted by the Americans for tank versus tank action was. Sherman crews also had concerns about firing from longer ranges, as the Sherman's high-flash powder made their shots easier to spot. This, and the U.S. Army's usual offensive tactical situation, often contributed to losses suffered by the U.S. Army in Europe. Even though the various gunsights fitted to the Sherman had fewer magnification settings than those fitted to German tanks, their gunners were able to use a secondary periscope that featured a far larger field of view than their German counterparts.
T4 High-Velocity Armor Piercing ammunition became available in September 1944 for the 76 mm gun. The projectile contained a tungsten penetrator surrounded by a lightweight aluminum body and ballistic windshield, which gave it a higher velocity and more penetrating power. The increased penetration of HVAP allowed the 76 mm gun to match the Panther's 7.5 cm KwK 42 APCR shot. However, its performance was heavily degraded by sloped armor such as the Panther's glacis. Because of tungsten shortages, HVAP rounds were constantly in short supply. Priority was given to U.S. tank destroyer units and over half of the 18,000 projectiles received were not compatible with the 76 mm gun M1, being fitted into the cartridge case of the M10 tank destroyer's 3-inch gun M7. Most Shermans carried only a few rounds at any one time, and some units never received any.
The British anticipated future developments in German armor and began development of a antitank gun even before its 57 mm predecessor entered service. Out of expediency and also driven by delays in their new tank designs, they mounted the powerful Ordnance QF 17-pounder gun in a standard 75 mm M4 Sherman turret. This conversion became the Sherman Firefly. Like the U.S. M1 gun, the 17 pdr was also a 76 mm gun, but the British piece used a more voluminous cartridge case containing a much bigger propellant charge. This allowed it to penetrate of unsloped RHA at and at using APCBC ammunition. The 17-pounder still could not penetrate the steeply sloped glacis plate of the Panther but it was expected to be able to pierce its gun mantlet at over ; moreover it was estimated it would defeat the Tiger I's frontal armor from. However, British Army test results conducted with two Fireflys against a Panther turret-sized target demonstrated relatively poor accuracy at long range; a hit probability of 25.4% at with APCBC, and only 7.4% with APDS. In late 1943, the British offered the 17-pounder to the U.S. Army for use in their M4 tanks. General Devers insisted on comparison tests between the 17-pounder and the U.S. 90 mm gun. The tests were finally done on March 25 and May 23, 1944; they seemed to show the 90 mm gun was equal to or better than the 17-pounder. By then, production of the 76 mm-armed M4 and the 90 mm-armed M36 were both underway and U.S. Army interest in the 17-pounder waned. Late in 1944, the British began to produce tungsten sabot rounds for the 17-pounder, which could readily breach the armor of even the Tiger II; these were not as accurate as standard rounds and not generally available.
After the heavy tank losses of the Battle of the Bulge, in January 1945, General Eisenhower asked that no more 75 mm M4s be sent to Europe: only 76 mm M4s were wanted. Interest in mounting the British 17-pounder in U.S. Shermans flared anew. In February 1945, the U.S. Army began sending 75 mm M4s to England for conversion to the 17-pounder. Approximately 100 conversions were completed by the beginning of May. By then, the end of the war in Europe was clearly in sight, and the U.S. Army decided the logistical difficulties of adding a new ammunition caliber to the supply system was not warranted. None of the converted 17-pounder M4s were deployed in combat by the U.S., and it is unclear what happened to most of them, although some were given to the British as part of Lend-Lease post-war.

The tank destroyer doctrine

General Lesley J. McNair was head of the Army Ground Forces from 1942 to 1944. McNair, a former artilleryman, advocated for the role of the tank destroyer within the U.S. Army. In McNair's opinion, tanks were to exploit breakthroughs and support infantry, while masses of attacking hostile tanks were to be engaged by tank destroyer units, which were composed of a mix of self-propelled and towed anti-tank guns. Self-propelled tank destroyers, called "gun motor carriages" were similar to tanks, but were lightly armored with open-topped turrets. The tank destroyers were supposed to be faster and carry a more powerful anti-tank gun than tanks and armor was sacrificed for speed. Armored Force and Tank Destroyer Force doctrine were developed separately, and it was not against Armored Force doctrine for friendly tanks to engage hostile tanks that appeared while attacking or defending.; tank destroyers were to engage numbers of enemy tanks that broke through friendly lines.
McNair approved the 76 mm upgrade to the M4 Sherman and production of the 90 mm gun-armed M36 tank destroyer, but he at first staunchly opposed mass production of the T20 medium tank series and its descendants, the T25 and T26 during the crucial period of 1943 because they did not meet the two criteria of the Army Ground Forces for accepting new equipment; they were not "battle worthy," and he saw no "battle need" for them. In fall 1943, Lieutenant General Devers, commander of U.S. forces in the European Theater of Operations, asked for 250 T26 tanks for use in the invasion of France; McNair refused, citing the fact that he believed the M4 was adequate. Devers appealed all the way to the War Department, and Major General Russell L. Maxwell, the Assistant Chief of Staff G-4 of the War Department General Staff, ordered the 250 tanks built in December 1943. McNair finally relented in his opposition, but still opposed mass production; his Army Ground Forces even asked for the tanks to be "down-gunned" from 90 mm to 75 or 76 mm in April 1944, believing the 76 mm gun was capable of performing satisfactorily. Marshall then summarily ordered the tanks to be provided to the ETO as soon as possible. Soon after the Normandy invasion in June 1944, General Dwight D. Eisenhower urgently requested heavy tanks, but McNair's continued opposition to mass production due to persistent serious mechanical problems with the vehicles delayed their procurement. That same month, the War Department reversed course and completely overruled the Army Ground Forces when making their tank production plan for 1945. 7,800 tanks were to be built, of which 2,060 were to be T26s armed with 90 mm guns, 2,728 were to be T26s armed with 105 mm howitzers, and 3,000 were to be M4A3 Sherman tanks armed with 105 mm howitzers. As a part of the plan, the British requested 750 90 mm-armed T26s and 200 105 mm-armed T26s. General McNair was killed in a botched air support mission in July 1944, and the path to production for the T26 tank became somewhat clearer. General Marshall intervened again and the tanks were eventually brought into full production. However, only a few T26 tanks saw combat beginning in February 1945, too late to have any effect on the battlefield.

Variants

The Sherman, like its M3 predecessor, was one of the first tanks to feature a gyroscopically stabilized gun and sight. The stabilization was only in the vertical plane, as the mechanism could not slew the turret. The stabilizer was sufficient to keep the gun's elevation setting within 1/8th of a degree, or 2 mils, while crossing moderately rough terrain at. This gave a hit probability of 70% on enemy tanks at ranges of to. The utility of the stabilization is debatable, with some saying it was useful for its intended purpose, others only for using the sights for stabilized viewing on the move. Some operators disabled the stabilizer.
The 75 mm gun also had an effective canister round that functioned like a large shotgun. In the close fighting of the French bocage, the U.S. Army's 2nd Armored Division tanks used Culin Hedgerow Cutters fitted to their tanks to push three tanks together through a hedgerow. The flank tanks would clear the back of the hedgerow on their side with canister rounds while the center tank would engage and suppress known or suspected enemy positions on the next hedgerow. This approach permitted surprisingly fast progress through the very tough and well-defended hedgerows in Normandy. Over 500 sets of these were fitted to US armored vehicles, and many fitted to various British tanks.
The 75 mm gun had a white phosphorus shell originally intended for use as an artillery marker to help with targeting. M4 tank crews discovered that the shell could also be used against the Tiger and Panther—when the burning white phosphorus adhered to the German tanks, their excellent optics would be blinded and the acrid smoke would get sucked inside the vehicle, making it difficult or impossible for the crew to breathe. This, and the fear of fire starting or spreading inside the tank, would sometimes cause the crew to abandon the tank. There were several recorded instances where white phosphorus shells defeated German tanks in this fashion.
A variant of the M4 Sherman was armed with the 105 mm M4 howitzer, which provided even more powerful high explosive armament. This variant was employed in three-vehicle "assault gun" platoons in tank battalions along with another 1 in each medium tank company to provide close fire support and smoke. Armored infantry battalions were also eventually issued three of these Shermans. The 105 mm-armed variants were of limited use against enemy tanks due to the poor anti-armor performance of the howitzer, which was not intended to fight other tanks, though a high explosive anti-tank round for the 105 mm howitzer was available for self-defense.

Armor

Turret

The turret armor of the 75 mm and 105 mm-armed M4 ranged from to thick. The turret front armor was 76.2 mm thick, angled at 30 degrees from the vertical, giving an effective thickness of. The opening in the front of the M4's turret for the main gun was covered by a rounded thick rotor shield. Early Shermans that had a periscopic sight for the main gun mounted in the turret roof possessed a small thick mantlet that only covered the hole where the main gun barrel protruded; the exposed barrel of the coaxial machine gun was vulnerable to bullet splash or shrapnel and a small armored cover was manufactured to protect it. When the Sherman was later fitted with a telescopic sight next to the main gun, a larger thick gun mantlet that covered the entire rotor shield including the sight and coaxial machine gun barrel was produced. 105 mm-armed Sherman tanks did not have a rotor shield, possessing only the mantlet to cover the opening in the turret front. The turret side armor was thick at a 5 degree angle from the vertical. The turret rear armor was thick and vertical, while the turret roof armor was thick, and flat.
Later models of the M4A1, M4A2 and M4A3 Sherman tanks were equipped with the T23 turret and the new 76 mm gun. This turret's armor was thick on the sides and rear, angled from 0 to 13 degrees from the vertical. It had a thick roof, which sat at 0 to 45 degrees from the vertical. The front of the T23 turret, which like the 105 mm-armed Sherman's turret, did not have a rotor shield, was protected by an unsloped thick cast gun mantlet. Combat experience indicated that the single hatch in the three-man 75 mm gun turret was inadequate for timely evacuation, so Ordnance added a loader's hatch beside the commander's beginning in late 1943. All 76 mm gun turrets had two roof hatches.

Hull

The Sherman's glacis plate was originally thick. and angled at 56 degrees from the vertical, providing an effective thickness of. The M4, M4A1, early production M4A2 and early production M4A3 possessed protruding cast "hatchway" structures that allowed the driver and assistant driver's hatches to fit in front of the turret ring. In these areas, the effect of the glacis plate's slope was greatly reduced. Later Shermans had an upgraded glacis plate that was uniformly thick and sloped at 47 degrees from the vertical, providing an effective thickness of over the entire plate. The new design improved overall ballistic protection by eliminating the "hatchways", while also allowing for larger hatches for the driver and bow gunner. The cast hull M4A1 for the most part retained its previous glacis shape even after the larger hatches were introduced; the casting, irrespective of the larger hatches, sat 37 to 55 degrees from the vertical, with the large majority of the piece sitting closer to a 55 degree angle.
The transmission housing was rounded, made of three cast sections bolted together or cast as one piece. It ranged from thick The upper and lower hull sides were thick, and vertical, while the upper hull rear was also thick, vertical or sloped at 10 degrees from the vertical. The lower hull rear, which protected the engine, was thick, sloped at 0 to 22 degrees from the vertical depending upon the variant. The hull roof was. The hull floor ranged from thick under the driver and assistant driver's positions to thick at the rear. The M4 had a hatch on the hull bottom to dispose of spent shell casings and to provide an emergency escape route. In the Pacific, Marines often used this Sherman feature in reverse to recover wounded infantry under fire.

Effectiveness

The armor of the M4 was effective against most early war tank and anti-tank weapons, but needed a compound angle to resist later German tank and anti-tank guns. The distinctive protruding "hatchways" of the early Sherman compromised the 56 degree-angled glacis plate, making them weak points where the effect of the glacis plate's slope was greatly reduced. In 1943, to make the thickness of these areas equal with the rest of the glacis plate, appliqué armor plates were fitted in front of them.
A Waffenamt-Prüfwesen 1 report estimated that with the M4 angled 30 degrees sidewards, the Sherman's glacis plate was invulnerable to shots from the Tiger's 8.8 cm KwK 36 L/56 and that the Panther, with its 7.5 cm KwK 42 L/70, would have to close in to to achieve a penetration in the same situation. Although the later-model German medium and heavy tanks were greatly feared, Buckley opined "The vast majority of German tanks encountered in Normandy were either inferior or merely equal to the Sherman."
Research for tank casualties in Normandy from 6 June to 10 July 1944 conducted by the British No. 2 Operational Research concluded that, from a sample of 40 Sherman tanks, 33 tanks burned and 7 tanks remained unburned following an average of 1.89 penetrations. In comparison, from a sample of 5 Panzer IV's, 4 tanks burned and 1 tank remained unburned, following an average of 1.5 penetrations. The Panther tank burned 14 times from a sample of 22 tanks and following 3.24 penetrations, while the Tiger burned 4 times out of a sample of 5 tanks following 3.25 penetrations. John Buckley, using a case study of the British 8th and 29th Armoured Brigades, found that of their 166 Shermans knocked out in combat during the Normandy campaign, 94 burned out. Buckley also notes that an American survey carried out concluded that 65% of tanks burned out after being penetrated. United States Army research proved that the major reason for this was the stowage of main gun ammunition in the vulnerable sponsons above the tracks. A U.S. Army study in 1945 concluded that only 10–15 percent of wet stowage Shermans burned when penetrated, compared to 60–80 percent of the older dry-stowage Shermans.
At first, a partial remedy to ammunition fires in the M4 was found in 1943 by welding appliqué armor plates to the sponson sides over the ammunition stowage bins, though there was doubt that these had any effect. Later models moved ammunition stowage to the hull floor, with water jackets surrounding each stowage bin. The practice, known as "wet stowage", reduced the chance of fire after a hit to about 15 percent. The Sherman gained grim nicknames like "Zippo", "Ronson". The latter story has been challenged on the grounds that the Ronson company did not begin using the slogan until the 1950s. and "Tommycooker". Fuel fires occasionally occurred, but such fires were far less common and less deadly than ammunition fires. In many cases, the fuel tank of the Sherman was found intact after a fire. Tankers described "fierce, blinding jets of flame", which is inconsistent with gasoline-related fires.

Upgrades

Upgrades included the rectangular armor patches protecting ammunition stowage mentioned above, and smaller armor patches in front of each of the protruding hatchway structures in the glacis in an attempt to mitigate their ballistic weakness. Field improvisations included placing sandbags, spare track links, concrete, wire mesh, or even wood for increased protection against shaped-charge rounds. While mounting sandbags around a tank had little effect against high-velocity anti-tank gunfire it was thought to provide standoff protection against HEAT weapons, primarily the German Panzerfaust anti-tank grenade launcher and the bazooka-derived Panzerschreck 88 mm calibre anti-tank rocket launcher. In the only study known to have been done to test the use of sandbags, on March 9, 1945, officers of the 1st Armored Group tested standard Panzerfaust 60s against sandbagged M4s; shots against the side blew away the sandbags and still penetrated the side armor, whereas shots fired at an angle against the front plate blew away some of the sandbags but failed to penetrate the armor. Earlier, in the summer of 1944, General Patton, informed by his ordnance officers that sandbags were useless and that the machines' chassis suffered from the extra weight, had forbidden the use of sandbags. Following the clamor for better armor and firepower after the losses of the Battle of the Bulge, Patton ordered extra armor plates salvaged from knocked-out American and German tanks welded to the turrets and hulls of tanks of his command. Approximately 36 of these up-armored M4s were supplied to each of the three armored divisions of the Third Army in the spring of 1945.

M4A3E2

The M4A3E2 Sherman "Jumbo" assault tank variant, based upon a standard M4A3W hull, had an additional plate welded to the glacis, giving a total thickness of, which resulted in a glacis of line-of-sight thickness, and over effective thickness. The sponson sides had thick plates welded on, to make them thick. The transmission cover was significantly thicker, and a new, more massive T23-style turret with of armor on the sides and rear and a thick flat roof, and a gun mantlet with an additional of armor welded on, which resulted in a thickness of 177.8 mm, was fitted. It was originally to be armed with the 76 mm gun, but the 75 mm was preferred for infantry support and was used. The higher weight required changing the transmission gear ratios to reduce maximum speed to 22 mph, and crews were warned not to let the suspension "bottom" too violently. 254 were built at the Fisher Tank Arsenal from May to July 1944, and arrived in Europe in the fall of 1944, being employed throughout the remainder of the fighting in various roles. They were considered "highly successful".

Mobility

In its initial specifications for a replacement for the M3 medium tank, the U.S. Army restricted the Sherman's height, width, and weight so that it could be transported via typical bridges, roads, railroads and landing craft without special accommodation. Army Regulation 850-15 restricted the widths of a tank to 103 inches and its weight to 30 tons. To conform to these standards the M4's initial tracks were 16.5 inches wide which produced ground pressure of 14 pounds per square inch and limited its off-road mobility. However, this greatly aided the strategic, logistical, and tactical flexibility and mobility of all Allied armored forces using the Sherman.
A long-distance service trial conducted in Britain in 1943 compared diesel and gasoline Shermans to Cromwell tanks and Centaur. The British officer commanding the trial concluded "They are utterly reliable.....I do not think they are quite as good as the Cromwell across country when they are running on rather worn rubber tracks and the going is greasy, neither does one get as smooth a ride, but they appear so infinitely superior in every other way particularly in reliability with a minimum of maintenance that this cross-country consideration is completely overweighed."
The Sherman had good speed both on and off-road. Off-road performance varied. In the desert, the Sherman's rubber-block tracks performed well, while in the confined, hilly terrain of Italy, the smaller, more nimble Sherman could often cross terrain that some heavy German tanks could not.
Albert Speer recounted in his autobiography Inside the Third Reich:
However, while this may have held true compared with the first generation German tanks, such as the Panzer III and Panzer IV, comparative testing with the second generation wide-tracked German tanks conducted by the Germans at their Kummersdorf testing facility, as well as by the U.S. 2nd Armored Division, proved otherwise; partly from their use of the characteristic Schachtellaufwerk interleaved and overlapped roadwheels, especially over muddy or other unfavorable terrain. Lieutenant Colonel Wilson M. Hawkins of the 2nd Armored Division wrote the following comparing the U.S. M4 Sherman and German Panther in a report to Allied headquarters:
This was backed up in an interview with Technical Sergeant Willard D. May of the 2nd Armored Division who commented: "I have taken instructions on the Mark V and have found, first, it is easily as maneuverable as the Sherman; second the flotation exceeds that of the Sherman."
Staff Sergeant and tank platoon sergeant Charles A. Carden completes the comparison in his report:
U.S. crews found that on soft ground, such as mud or snow, the narrow tracks gave poor ground pressure compared to the Panther and Tiger. The U.S. Army issued extended end connectors to add width to the standard tracks as a stopgap solution. Duckbills began to reach front-line tank battalions in fall 1944, but were original factory equipment for the heavy M4A3E2 Jumbo to compensate for the extra weight of armor. The M4A3W HVSS Shermans and other late models with wider-tracked suspensions corrected these problems, but formed only a small proportion of the tanks in service even in 1945.

U.S. variants

Vehicles that used the M4 chassis or hull derived from M4:
The Sherman was extensively supplied through by Lend-Lease to Britain, the Soviet Union, and Free France. Britain received 17,181 in various models, mostly M4А2s and M4A4s. The Soviet Union was shipped 4,065 M4., or 4,102 M4. Еnrolled 3,664. The Free French were the third largest recipient, being given 755 during 1943 and 1944. At least 57 Shermans were also delivered to other U.S. allies.
A similar vehicle was developed in Canada from January 1941, known as the Ram tank. Like the Sherman, this developed from the M3 Lee's chassis and its powertrain, but like the Sherman, was based with a fully rotating turret. One improvement was the use of all-steel 'CDP' tracks, which although an inch narrower than the early M4 steel and rubber pad tracks, were cheaper to produce and gave better traction. Suspension units and roadwheels remained the M3 vertical volute pattern, with the idler above the mounting bracket, rather than the M4 development with the idler moved behind the mounting bracket to give more room for suspension travel. The Ram had a distinctive turret with a bolted flat-faced mantlet and the UK 6 pdr gun, with the hull machine gunner housed in a rotating turret based on the M3 'Lee' cupola, rather than the simpler ball-mount that was becoming universal for tank hull guns. Production facilities for the Ram were constructed at the Montreal Locomotive Works, with the aid of Alco, but the large armor castings for turret and hull were supplied by General Steel Castings in the US. Greater Sherman production and availability meant that the Ram was never used in action as a gun tank, being either used for training or converted to Kangaroo armoured personnel carriers.
A later Canadian medium tank, produced from late 1943, was the Grizzly, an adaption of the Sherman M4A1. This differed only in details, such as the CDP tracks, British radio equipment and the British 2" smoke mortar in the turret roof. 188 were produced.
After World War II, Shermans were supplied to some NATO armies; Shermans were used by U.S. and allied forces in the Korean War.
Shermans also went to Israel. The Israeli up-gunned 75 mm M-50 and 105 mm armed M-51 Super Shermans are remarkable examples of how a long obsolete design can be upgraded for front-line use. They saw combat in the 1967 Six-Day War, fighting Soviet World War II-era armor like the T-34/85, and also in the 1973 Yom Kippur War, proving effective even against newer, heavier Soviet tanks like the T-54 and T-55.
Paraguay retired three Shermans from the Regimiento Escolta Presidencial in 2018, which marked the end of service of the final Sherman tanks in use anywhere in the world.

Former operators