The Sherman tank is perhaps the most vilified weapon of World War II. One TV show listed it as an engineering disaster. Belton Cooper wrote a book about the Sherman program titled Death Traps. Given that Cooper recovered tanks for the 3rd Armored Division in World War II perhaps the hyperbole is somewhat deserved. Certainly the M4 was not the tank most would choose to take on a German Panther or Tiger. Yet at the end of the day Sherman tanks took their victory parades in Germany. Shermans served for thirty years after World War II, long after the last Panther had been retired to museum or private collection. The Sherman may not have been the best tank of World War II -- that honor belongs to the Russian T34, which fought from beginning to end, inspired the bigger German designs, and continues to serve around the world today. But the M4 Sherman was good enough to win that war and help win a few more decades after its birth.
The genesis of the Sherman really begins in 1939, when the entire tank development budget was $135,000, a paltry sum even then. The US had no doctrine whatsoever to guide soldiers on how armor was to be used. The Army experimented with light tanks but nobody could agree on what tanks were really supposed to do or what kind of tanks to build. Confused doctrine was hardly an exclusively American problem. The British and French armies had their own disputes, and mostly divided their spending between so called "cavalry tanks"; light, fast tanks suitable for scouting and exploitation, and "infantry tanks" which were heavily armored and designed to bull their way through the teeth of the defense. But one side had come to an agreement on how to fight with armor- the Germans.
The Treaty of Versailles had forced Germany into a very small army and stripped it of any tanks or airpower. Limiting German equipment and manpower did not nothing to inhibit German thinking or lessen their sense of grievance and weakness. Necessity forced German army to become a superbly trained, tactically sophisticated force favoring maneuver because it could not play the attrition game with even the least of its neighbors. Tested in a series of superbly designed maneuvers and tactical problems, the German Army produced an officer corps much more ready then any of its neighbors when Germany began to re-arm. The Spanish Civil War became a laboratory for both Nazi Germany and the Soviet Union. The Germans developed the Messerschmitt Bf 109 into a superb fighter backed with correct doctrine, and tested out the light Panzerkampfwagen I and II tanks. While many observers saw the war proved anti-tank guns would dominate tanks, the Germans simply realized their tanks were too light and began developing the backbone of their WWII panzer divisions, the Panzerkampfwagen IV.
Guarded by two oceans and feeling above European squabbles, America watched the Wehrmacht's rapid and skillful dissection of Poland in 1939. Of course, the foe was mere Poland. Nobody really thought Poland or Czechoslavakia could defend themselves against a re-armed Germany. The British and French were supposed to be made of sterner stuff. Most predicted another long, brutal and bloody slugfest like the First World War. Then the Panzer divisions burst through French B divisions in the Ardennes. The Germans had good equipment, a modern tactical doctrine designed around mobility, concentration of force and combined arms applied by a combat experienced army and air force trained and equipped for mobile battle. In a few weeks the proud French Army was struggling to buy time for British soldiers to escape across the English Channel. Isolationist America began to wake up.
Between the wars the U.S. Army could be characterized primarily by neglect. The tiny tank corps used their 1917-vintage Renault tanks until 1933. No Army can overcome decades of neglect overnight, but the U.S. tried. Congress voted money. Given that America produced more then half the entire world's supply of steel in 1941 America had both the funds and industrial base to respond. The Army began expanding in response to warlike moves around the world. Money finally became plentiful for tank development. But while Congress could vote more money, they could not grant more time.
Haste became the defining characteristic for the Army's tank program as it was immediately clear the M2 medium and M2 light entering service were already obsolete. The Army looked hard at what had happened in Europe and what was happening in North Africa in determining their requirements for what became the M4 Sherman. Most tank designers start by determining a tank's weight. Armor is very heavy and the U.S. Army realized that it would be fighting at the end of a very, very long logistics chain. Tanks would have to be loaded on rail cars, then transferred to a ship, then lifted off the ship and onto a dock even if the tank didn't need to be moved into an LST or some other type of landing craft. Which it would if Europe were to be liberated. It would have to cross bridges, including temporary bridges erected by engineers. Weight and size greatly affect loading and shipping problems as a single ship can carry far more light tanks then heavy. A liberty ship was rated to carry either 440 light or 260 medium tanks (like the Sherman). Heavier cranes are required for loading. A heavier tank also requires a bigger engine and much stouter transmission. It burns more fuel. Many of the Panther's problems stemmed from the tank ending up 10 tons heavier then the tank's original 28 ton design weight. Panther transmissions required very careful handling to avoid failure. Panthers sucked gasoline.
Doctrine was still being developed, but it very much influenced the Sherman's design, particularly with regard to firepower. The Brits were howling for a 75mm gun capable of defeating German armor at range. U.S. tank doctrine suggested that tanks were to be employed breaking through prepared enemy defenses. The M2/M3 75mm gun first installed in the Sherman fired an armor piercing shell capable of defeating any of Germany's 1940 tanks, and an outstanding high explosive round for destroying fixed defenses. If heavier tanks came along, they were to be fought and defeated by the tank destroyer force. TDs were faster, lighter and carried high velocity guns designed to defeat enemy armor.
The weight of the tank was determined in part by the required armor, which in turn dictated the engine. It was decided to armor the Sherman to defeat the 37mm gun the Wehrmacht was using at the time. Defeating the 37mm required about 50mm of armor. Any tank capable of resisting such guns would end up weighing about thirty tons, which in turn mandated an engine of around 400hp for the tank to possess enough mobility to exploit breakthroughs. Unfortunately, the Army had devoted not one red cent to tank engine design before 1940. Engine development takes a minimum of one year just to get prototypes out for testing. Yet the Army needed tanks coming off the lines no later than 1941! Lacking a dedicated tank engine the Army started looking at aircraft engines which have to be light, powerful and reliable. Market conditions had led the US aircraft industry to concentrate on radial designs, where the cylinders stick out from a central core like spokes. The M2 and M3 light all used radial engines, which at least had the virtue of not needing a cooling system. Continental made a 9-cylinder radial, the R-975, which made the required 400hp. The motor was very wide, but it was ready in 1940 and it made the needed power reliably at the right weight. The vertical-volute suspension (VVSS) had been used on the M1 combat cars, the M2 Medium and the M3 Stuart and so was well-developed. VVSS also took up zero space inside the hull. Haste led Army engineers to grab those off-the-shelf components and design around them. There simply was no time to start from scratch.
The Sherman would employ a new three man turret which would not be ready before late 1941 or 1942. Needing something, anything in the field with a 75mm gun by early 1941 American took proven components it had, the R-975 and the VVSS, mounted a 75mm M2 gun into the hull casemate, and capped it with the two man turret from the M2 light tank, installed and pronounced it an M3 (medium) whom the Brits named General Grant. The tank had a really tall silhouette and the early riveted hulls were prone to spalling if hit, but the M3 was reliable and the Brits loved the 75mm. The M3 was nothing more then a stop-gap design but it was well appreciated when it arrived for the 75mm and its mechanical reliability (most British tanks developed after 1939 were rushed into production without proper development due to the fear of imminent invasion).
From day one the Army laid heavy stress on getting the tanks built so they would be on the battlefield where they were needed. Early in the war engine shortages led to the production of several variations of the tank, as the design and the ability to manufacture it had to be developed together. The M4 and M4A1 (which had a more rounded cast hull, rather then the welded hull of other models) used the R-975. Two GM 6-72 diesel engines powered the M4A2 models, which were shipped to the Russians and preferred by the Marines. The Chrysler multibank represented the ultimate cobbled together engine, when Chrysler engineers wrapped five six-cylinder automobile engines around a central crank. The motor required a lot of regular maintenance, and a stretched hull, but when it got said maintenance proved reliable and durable. Britain got most of these M4A4 models as the US preferred to keep everyone using the same motor. Later on the 500 (or 450hp) Ford GAA V-8 became the preferred engine. The GAA (also a converted aircraft engine) proved compact, reliable and powerful enough the tank could be started in second gear. GAA powered Shermans were designated the M4A3.
In 1939 most tank hulls were riveted together or cast. Rivets allowed the use of flat plates, but had the bad habit of breaking off and flying around inside the tank when it took a hit. The cast hull of the M4A1 was considered ballistically superior but required a very large casting, a huge bottleneck. Very few firms proved capable of such castings. Improvements in welding technology made it possible to weld together a hull made out of flat plates of rolled homogeneous armor (RHA). RHA hulls (used in all models of the M4 except for the M4A1) proved much easier to produce and ended up with superior ballistic resistances as the rolling process toughened the armor. Early versions of the M4 had frontal armor inclined at a very good sixty-three degrees but direct vision slots for the driver and assistant-driver proved to be shell traps. The turret armor in front of the gunner also proved a weak spot. But the tank was designed for easy maintenance with a removable transmission cover in the front hull, and good access elsewhere. It was also designed for mass production.
The R-975 radial defined the hull's shape. The wide radial engine elevated the tank's driveshaft which in turn elevated the fighting compartment as the turret basket had to be raised to clear the driveshaft. The need to elevate the turret led to the characteristic turtleback hull and height. Later engines like the Ford GAA permitted a lower silhouette, but the hull remained largely unchanged to keep the production lines rolling.
The Sherman had a crew of five, excellent as tanks require lots of maintenance. The driver sat on the left and the assistant driver on the right of the hull. The assistant driver's primary job was to operate the .30 caliber bow machine gun. The tank commander, gunner and loader rode in the turret. The tank was steered by braking through two levers, typical for the time, but left the tank incapable of the "pivot turn" the Panther and all modern designs can execute. The Panther could pivot in its own space, keeping its thickly armored front aimed toward the enemy. The Sherman had to move to turn. The tank America took to war in 1942 was a cobbled together mix of off the shelf parts and new bits. But it was easy to produce, fast, fuel efficient and reliable. And in 1942 it was better then anything the Germans had to offer. The Panzerkampfwagen IV had been shipped with a low-velocity 75mm howitzer which was all but useless against tanks. Most PzKw III tanks, intended for anti-tank duty had been equipped with the 37mm cannon against Hitler's direct order. The German tanks had lower silhouettes, but when it was introduced the rush-job Sherman was the best in the world. Certainly it was the best tank when Montgomery won the Battle of El Alamein.
Still, there is no more Darwinian process then combat. The Sherman had been built with 1942 in mind with limited thought for the future. Unfortunately for the Allies the Germans were moving on. In 1940 they met the heavily-armored British Matilda infantry tank. Had the Wehrmacht not pressed their 88mm Flak anti-aircraft gun into emergency service the Matilda might very well have changed the entire course of the battle for France. But what really woke the Germans up was the Russian T34. Fast, heavily armed and highly mobile with well-shaped armor the T34 was well ahead of anything anybody possessed. German soldiers began calling their 37mm anti-tank gun "the doorknocker" because that's all it did to a T34. The Germans designed the later Panther and Tiger tanks to incorporate the lessons taught by the T34. They also deployed much heavier anti tank guns. The PzKw IV had a roomy turret and turret ring which made it easy to install a high-velocity 75mm gun well suited for killing tanks. In fact the 50mm replacement for the Pak 36 was already being deployed in 1940! By D-Day the 50mm had mostly been replaced by the high-velocity 75mm Pak 40. So the Sherman ended up fighting anti-tank guns two generations later then the gun its armor was designed to defeat.
By 1943 the Panther and Tiger I had begun to appear in response to German combat experience. The Tiger had tremendous armor from all angles but required an enormous amount of labor to produce. The Panther was much less expensive but was rushed into combat, which colored early assessments of the tank. Models of both tanks were captured and tested, but the armor board failed to truly appreciate the threat of either tank. The big cats were correctly seen as complex and hard to produce but it was expected that what numbers they could produce would be sent where they were most needed--- the Russian front. Overconfidence was shown in the effectiveness of existing guns, and doctrine declared the Sherman was not intended to fight other tanks. Tank destroyers would handle the few big German tanks on the Western Front. In fact the Germans solved most of their tanks' teething problems, and put most of the big new tanks in the West, in hopes of defeating any Allied invasion before it could become a threat. While many in the Army Ground Forces wanted the Sherman to carry a bigger gun, up to and including the 90mm that would be later installed on the M26 Pershing, nothing came of it. The army wanted tanks in the field, not on the drawing board. The result was that the Sherman began 1944 lacking in both firepower and protection.
Only the British Army really took the Tiger and Panther threat seriously. They had some good new tanks on the drawing board, but the exceptional Centurion would arrive too late to fight. So they did what they could, mounting the 75mm OQF 17-pounder in a number of Sherman's they named "Fireflies". The 17-pounder fired a poor high explosive round and gave off a fearful muzzle blast, but in penetrating power it was every bit the equal of the German 88mm. The Sherman Firefly remained the only version of the Sherman capable of killing the big Germans at range throughout the war. Fireflies were issued to British units with about one provided to every troop of four. The Germans quickly learned to find and shoot at the Fireflies first, greatly abetted by the fact that the 17-pounder's barrel was about six feet longer then that of the standard gun.
It was wise of the British Army to create the Sherman Firefly. Northern France was where the Sherman really earned its nickname 'Ronson', after the American lighter whose manufacturer claimed it would "light first time, every time". East of Gold and Sword beaches lay the city of Caen. The country was relatively open there with fewer of the constricting rivers, ridges and hedgerows west of the Normandy beaches. The British Army drew that sector, and it was seen as good tank country by both sides. So the Germans packed most of their armor into that sector, including most of their Panthers and the one Tiger company that did see combat at Normandy. Here German tanks with their very high velocity guns and thick frontal armor could dig in hull down, meaning only the turret was exposed to fire. Here they could see Allied tanks approaching at very long range. Here they could engage to the extent of their equipment. The result was very hard going for Montgomery's troops and very high casualties, abetted by a chronic shortage of British infantry.
The conditions the British Army faced during the Battles for Caen entirely favored the big German tanks. The big cats were facing tall, more thinly armored tanks with equipped with much less powerful guns (outside of the Fireflies). Early Shermans stored much of their ammunition high in the hull sponsons, and tended to pile extra ammo loosely in the turret. Under ideal conditions and on defense the big German iron tore a swath through British and Canadian armor. To the west of Normandy lay the bocage country, narrow confined, lines that were mined and left the tanks liable to ambush.
Thankfully by D-Day improved versions of the Sherman had begun to appear. The 18-litre Ford GAA V-8 had finally arrived in quantity. The GAA was another adapted aero engine, an all-aluminum, water-cooled, DOHC 32-valve motor of 450-500hp. GAA engined versions were known as the M4A3 and received other improvements. Most ammunition storage was moved below the turret and into armored boxes in the floor filled with flame retardant glycol. The front glacis plate was changed to forty-seven degrees without the vulnerable front vision slots and provide easier exits for driver and co-driver. Later the VVSS suspension gave way to the horizontal volute spring suspension system (HVSS) which had a much better ride and tracks 23" wide for flotation better then even a Panther.
A new, greatly improved turret arrived, with a new gun. The Army was not so blind as to realize the Sherman had become outgunned. A larger three man turret from the experimental T23 was chosen. The loader got his own escape hatch. The tank commander's hatch was enlarged and given vision blocks so he could still see with the tank buttoned up. Best of all was the replacement of the M3 with the higher-velocity M1 76mm. The gun fired an inferior high explosive round, but it was much more effective against German armor. But without extremely rare HVAP ammunition with its tungsten core penetrator, it still had difficulty penetrating the panther's front even at point blank range. Still, the 76mm was much better and made up for the high-velocity 75mm the Germans started installing in their mainstay, the PzKw IV. With the T23 turret, GAA power and HVSS suspension the M4A3E8 became the ultimate version of the Sherman and served in Israeli and the US National Guard into the 1970s.
The Army also realized the tank needed more armor. They sped production of the heavy M26 Pershing, which would lead the next generation of US tanks. But all knew Pershing could not make it to the battlefield before 1945. A special 'Jumbo' version of the M4A3 Sherman was created, the M4A3E2. Armor was thickened to six inches on the transmission cover with a 10" thick gun mantlet. Jumbos received a new, much more heavily armored (and enlarged) turret. Jumbo Shermans shook off hits that would have passed through both sides of the standard tanks yet the tank's mechanical solidity was such that even additional ten tons of armor did not severely impact the Jumbo's reliability. Jumbos were delivered with the 75mm M3, a better gun against fortifications, but most were later replaced with the 76mm. The tank proved very popular, as Jumbos could absorb hits even from a Panther and keep fighting. They were slower with a maximum speed of 22mph, but the extra armor more then made up for the lost speed. They were so appreciated that General Patton ordered the creation of 'expedient jumbos' by welding the armor from cut up German tanks on to the front of HVSS equipped Shermans.
"Battle worthiness" was one requirement where the Sherman always excelled. Whereas a Panther with 1,000 miles on the clock needed a total factory rebuild, many Sherman's doubled that number and kept going with only routine maintenance. Shermans were fast, fuel efficient and easy to work on. They were also relatively easy to produce in quantity. While the German Tiger gets lots of press the Germans could only field a company of them to block the British Army before Caen. Panther reliability improved greatly after their dismal 1943 debut, but Shermans proved even more reliable. The Germans lost a lot tanks to breakdowns. A superior tank broken down alongside the road is not near so good as lesser vehicle that's out there slugging. The US produced enough Shermans to not only equip its armored divisions, much of the British Army and some of the Soviet Army plus fielded enough Shermans to attach a dedicated tank battalion to each American infantry division. Thus provided, a single American infantry division had more armor them most Panzer divisions. With T34 production also high, the Wehrmacht got a lot of practice fighting enemy tanks.
The Sherman also enjoyed other advantages. Ergonomics matters. While the PzKw IV started the war with a powered turret by the end of it the turret was hand-cranked to ease production. All Shermans came with powered turrets with a high slew rate. A Sherman could rotate its turret in a complete circle in one third the time of a Panther. The gun was gyrostabilized vertically, and while the system gave problems when it worked the gunner was able to sight on targets while moving, even if the stabilizer did not give the tank a true shoot on the move capability. The sight in a Panther was a wonderful telescope with very high quality optics. But the Sherman's sight included a padded full face mask so a Sherman gunner could use his sight while the tank was moving. In ambush, the Pather was the better vehicle. But in a meeting engagement, where neither could be sure where they would meet the enemy, the Sherman got off the first shot more often then not.
Most commentators point out how bad the Sherman was by comparing it to a Panther or Tiger. Certainly if you put each tank at opposite ends of a large field and let them slug it out no one would bet on the Sherman. But war is not gladiatorial combat. War is not decided by a single weapons system. Wars are won by systems with a wide range of capabilities which fit the needs of the combatants. The Tiger was virtually impervious to Sherman fire except from behind, but they were so expensive the Germans could never field more then a handful. Panthers were much more affordable, but could be killed from the side by all versions of the Sherman at normal combat ranges. In 1944 the German army suffered from severe fuel shortages yet both the Panther and Tiger were fuel hogs, restricting their use. Shermans were everywhere. All versions of the Sherman could fight and beat the one tank the Germans could produce real numbers, the PzKw IV.
When a Panther or Tiger could dig in on defense and fire from long range they dominated. But that was not so true under other circumstances. One case in point is the Battle of Arracourt fought from September 18-29, 1944. The German Fifth Panzer Army was re-equipped with new Panthers and sent to check Third Army's advance toward Lorraine in the early fall. On paper the attack should have been a mismatch. The German commander, Hasso von Manteuffel, was a proven veteran of tank combat on the Eastern front. The Panther and Tiger had dominated during the series of battles for Caen after D-Day. Fifth Panzer Army had been given new Panthers and von Manteuffel's tank commanders enjoyed long combat experience.
But there were chinks in the German armor. While German tank commanders were veterans their crews were not. Inexperience particularly afflicted Panther drivers as the tank's transmission had been designed for a much lighter tank. Fifth Panzer's American opponents, the U.S. 4th Armored Division, was a hot unit. Fourth Armored enjoyed an outstanding commanding general, John S. Wood, and fine battalion commanders including Creighton Abrams, (who would enjoy less success in Vietnam). American tank crews were by and large better trained then their depleted German adversaries. Heavy fog negated American airpower, but fog and the rolling country prevented the big German tanks from playing their strong suit, digging in and engaging at range. The result was a meeting engagement. Here the superior speed, turret slew rates and American training turned what looked on paper like a mismatch into a decisive defeat for German armor. In fact, 4th Armored beat Fifth Panzer Army so decisively that Patton wasn't really aware he was facing a major counterattack for several days! Had Arracourt not occurred at a moment when Patton's fuel supplies were about to be choked off the battle might have been more celebrated. Without fuel Third Army was unable to exploit the defeat one armored division inflicted on a German Panzer Army. Logistics, not the Panther, stopped Third Army's rapid advance across Europe.
Few would argue the Sherman was the best combat tank of World War II, as Steven Zaloga has. Most award that honor to the Panther or T34. Yet Easy Eight Shermans outperformed the T34/85 in Korea. If the Sherman was good enough to serve and fight thirty years after the end of WWII, if it was good enough to be on the winning side of most of the wars it fought and if it was good enough to serve long after the last Panther was retired the Sherman tank was more then the 'Death Trap' Belton Cooper called it. The balance of low cost, high reliability combined with an adequate balance of firepower, protection and ergonomics made the tank into a war winner. Its reliable chassis made it the basis of many different types of military vehicles. In fact, a Canadian company produces Sherman parts to this day because the chassis proved so reliable as an oil drilling support vehicle in arctic conditions. It wasn't the greatest ever, but the Sherman belongs with the greats. Not bad for a rush job.
- M4 R975 Radial engine, M2 and M3 75mm gurn
- M4 (105) replaced 75mm with short-barreled 105mm howitzer for infantry support
- M4A1 as above with cast hull, identified by rounded sponsons and glacis. Many were upgunned to 76mm
- M4 DD Amphibious variant with prepared for the D-Day invasion
- M4A2 with 2 GMC 6-71 diesel engines. Lend lease to the Soviet Union and used in the Pacific by Marines.
- M4A3(75) Most common variant. All A3 variants were powered by the Ford GAA V-8. Initiated wet ammunition storage, later the 47 degree glacis. One piece transmission cover.
- M4A3(76) replaced M2 and turret with larger T23 turret and 76mm
- M4A3E2 "Jumbo" sherman assault tank. Up armored to 4" on front glacis, turret front and 8" gun mantlet. Heavy, slow but hard even for Panthers to kill. Track extenders permanently installed to carry additional weight.
- M4A4 same as M4 with Chrysler Multibank Engine. Sold to Great Britain. Slightly extended hull and most Fireflies started out as M4A4s
- M4A3E8 'Easy Eight" Same as M4A3(76) except Verticle Volute Suspension system replaced with Horizontal Volute Suspension. Tracks widened to 23" Final Sherman variant and retained in service long after the war. Saw front-line duty in Korea
- M4A3R3 Flame thrower tank, known as a "Zippo" (after the cigarette lighter)
- M4A5 Canadian produced Shermans
- M4A6 Very rare, and used a Caterpillar D200 (later called the Ordinance Engine RD-1820) diesel engine modified from Wright radial aircraft engine. Had a true multi-fuel capability.
The U.S. also produced bulldozer, anti-mine and Shermans equipped for launching rockets. Israel, Egypt, Chile and other countries have modified many Shermans for their own uses, including some using a French 105mm gun. Chili kept their M50/60 Shermans in service until 1989.
Vehicles using the Sherman Chassis
- M7 Priest Standard allied SP artillery vehicle 105mm howitzer. M7B only.
- M10 Wolverine Most common US Tank Destroyer. 76mm gun.
- M36 Jackson 90mm gun tank destroyer. Only US vehicle before the M26 Pershing capable of defeating the Panther and Tiger head on at range
- M32 Tank Retriever. Saw service into the 1980s.
- M74 tank retriever. Basically an improved M32.
- M4 Mobile Assault Bridge
An M4A3 being driven. This is a 1943 production tank, note the applique armor welded over the direct vision slots, sponson magazines and the gunner's position in the turret. It has the earlier hull. http://www.youtube.com/watch?v=__K2BzxR2BY
The "engineering disasters" video linked at the top of this article is useful but contains many factual errors. For example ammunition fires were the primarily the cause of tank fires, not gasoline.