In the spring of 1940, the U.S. Army was working on the design of a medium tank. The design was for a 20 ton vehicle mounting 5.30 cal. machine guns and a 37 mm gun. Classified as the M2, it was ready to enter production just as the German army was completing the conquest of France. In light of the fact that the Germans were reportedly using a 75 mm in their Pzkw IV, General Chaffee, just appointed to the new position of Chief of Armored Forces, met with senior members of the Ordnance Department and decided that any new tank must mount a 75 mm gun. The M2s were thus obsolete even before production. Now the problem was to design a new vehicle as quickly as possible.
To fill in the gap until a new tank could be produced it was decided to use as much of the existing M2 design as possible and build an interim tank. Fortunately the designers of the M2 had already drawn up plans for a self-propelled gun based on the M2 chassis and mounting the 75 mm field gun. These plans were modified for the mounting of the 75 mm anti-tank gun in a sponson on the right side of the hull; the original 37 mm gun and turret were retained and mounted offset to the left on top of the hull.
The resulting tank was the M3 Grant/Lee. The M3 weighed approximately 32 tons and had a maximum armor of 50 mm. on the hull front and turret front. The designs were finalized in March of 1941, and the pilot models were completed in April. The Grant started production in April of 1941 and ended production in December of 1942; in that time about 5,500 M3 were produced.
Design of the M4 started in April 1941, and the prototype of the M4 finished trials in October. The same lower chassis was retained from the M3. The upper hull was to be cast, but only a few plants in the U.S. had the ability to cast that large a hull. Because of this welded hulls were also used. The welded hull was classified as the M4 and the cast hull as the M4A1. Production of the M4 Sherman was started in the spring of 1942 as the M3 was phased out.
While American production was embarking on this crash course of tank design and production, the U.S. Army was attempting to formalize doctrine on the use of the tank. There were two schools of thought; the first group felt that the tank was a general purpose weapon and was to be used to destroy other tanks as well as infantry and equipment and to force a breakthrough of the enemy lines. The second group felt that the tank was for infantry support and for use in exploitation of a breakout but not in making the breakout.
Unfortunately, doctrine in the army was under the jurisdiction of Army Ground Forces (AGF), commanded by General McNair. McNair was an artillery man and believed in the second theory. He felt that enemy tanks were best dealt with by an anti-tank gun, either towed or self- propelled. In support of this the Tank Destroyer Command was established and a separate school was set up outside of the jurisdiction of the Armored Forces.
The other half of the armor team is the self-propelled tank destroyer, again based on the M4 chassis. Testing of a vehicle began in November of 1941 and the prototype went into production in June of 1942 as the M10. The M10 was based on the M4A2 Sherman and mounted a 3 inch anti-aircraft gun modified for anti-tank use. It weighed about 29 tons. Production ended in December of 1943 by which time 6,596 M10s had been built.
Thus, as 1942 came to a close, the U. S. Army found itself fighting in North Africa against the German Army. The Americans were in very good shape. The main tank in use was the M4, mounting a 75 mm L38 gun; it also had the M10 tank destroyer mounting a 3 inch gun (76.2 mm L53). Unfortunately, many tank destroyer units were still using the M3 half-track mounting the 75 mm L31 field gun or even 3/4 ton trucks mounting 37 mm guns. These last units suffered heavily due to poor vehicles and improper doctrine. (The Tank Destroyer School taught its units to be very aggressive and to hunt out enemy tanks. Given that even the best U.S. TDs were lightly armored, any attempt to close with a tank was very foolish. Patton criticized the tactics of the TDs. Subsequently, their training was changed to emphasize aggressive reconnaissance and ambush tactics for destroying tanks.)
The German army in North Africa was mainly Pz III and Pz IV tanks supported by Stg IIIs and Marder HIs. The Pz III mounted a 50 mm, L42 or L60 gun. The original Pz IV mounted a 75 mm L24 gun but later models mounted 75 mm L48 guns. (2 The L designation is the length of the barrel as a ratio of the diameter. In the US Army, the chamber is not included; in the German Army, the chamber length is included, so the two do not correlate. The U.S. 75mm M6 was L37.5; if you include the chamber it is L40.1. The 76mm is 52 and 54.6. The 90 mm is 50 and 52.3.)
The Stg IIIs and Marders mounted the same guns as the Pz IVs. Generally the M4 were superior to the Pz III and equal to the Pz IV, although the L48 gun gave the Germans a better chance of a kill at longer ranges.
The problem for the U.S. at this point was that the Tiger I was entering service. While the Germans had three companies of Tigers in North Africa, they never had more than about twelve in service at one time. The U.S. felt that in small numbers they could be dealt with by existing tanks. Thus, while the U.S. Army Ordnance Department continually designed new and better tanks, the AGF and Armored Forces were not interested in any new vehicles.
In 1943 the U.S. Army fielded no new tanks. It only introduce the M18 tank destroyer as a supplement to the M10. The Germans, on the other hand, introduced the Panther, new models of the Pz III and IV, and the Elephant. They also continued to increase the number of Tiger I tanks, something the U.S. Army had not predicted. By the end of the year the USSR introduced the T34/85, KV-85, SU-85, SU-122 and SU-152. It was the introduction of these new Soviet vehicles that continued to drive the Germans to produce bigger tanks.
The second U.S. tank destroyer was not based on the M4 chassis but was built from the ground up for the role as a TD. The M18 was much lighter than the M10 (20 vs. 30 tons) and was thus faster (45 mph vs. 30). It mounted a modified 3 inch gun, the 76mm M1 (The 76 mm used the same projectile as the 3 inch gun but a different shell case.) (later mounted in the M4). Because of its light weight, high speed, and low silhouette, the M18 was an improvement over the M10 which had turret and gun problems. What it sacrificed, however, was armor, and even the lightest German guns could knock it out.
Because of the doctrine of using tanks to fight infantry, the AGF also resisted the request to put the 76 mm gun (The barrel was lighter than the 3 inch gun, and it used the same breach ring as the M3 75 mm. Thus it could be easily mounted in the Sherman turret. However, tests showed that the gun (originally 57 caliber) was barrel heavy; to compensate for this, 15 inches were cut off the end of the barrel and blocks were welded to the breach to balance the gun. This left the turret badly out of balance since the 76 mm weighed much more than the 75 mm. To cottec this, an 800 1b. counterweight was added to the rear of the turret. In the end, however, the Armored Forces rejected the idea because the turret was too cramped. I find this a weak argument in light of the fact that the British mounted the 17 pdr. gun in the same turret.) in the M4.
While it was true that the 76 mm. could penetrate about one inch more of armor at all ranges than the 75 mm, the HE shell was smaller. The explosives in the 75 mm HE weighed 1.47 lbs. versus .86 lbs. for the 76 mm. This meant less effectiveness in the primary role, destroying infantry and equipment. The testing of the 76 mm was conducted in August of 1942; in April of 1943 Ar. mored Forces turned down the mounting of the 76 mm in the original M-4 turret. The final solution to the problem was to use the turret from the T-23 heavy tank that was designed with the 76 mm in mind.
Since the turret ring in both vehicles was 69 inches it was an easy modification, (The U.S. capitalized on the fact that all medium and heavy tanks and tank destroyers had a 69 inch turret ring. The M-36 turret was mounted in the M-10 and M4A3. The Pershing turret was even mounted on the M4 as a test in July of 1944, but it was not produced because it was believed that the M-26 would be in service at about the same time as this modification could reach the front.) and was adopted in May 1943. By July of 1944 some battalions were equipped with 1/3 76 mm gunned M4s. By 1945 most had 1/2 76 mm.
With the introduction of the 76 mm into the Sherman several other modifications were included. The front armor of the hull was increased from 53 mm at 56 degrees to 63 mm at 47 degrees. This was done to simplify production and to eliminate the bulging in the armor at the driver and assistant driver positions. It also allowed larger hatches for these two crew members. Wet stowage was also introduced. This decreased the chances of fires due to ammunition being ignited by hits, a problem that plagued early Shermans.
In September of 1943 the Army began testing the 90 mm antiaircraft gun as a replacement for the 3 inch gun in the M10. The new vehicle went into production as the M36 in November of 1943; 187 M4A3 hulls had M36 turrets mounted on them as a stop gap measure. Also many M10s were converted to M36s by simply changing the turrets. The total production of M36s was 1,682 (not including 724 M10 conversions).
In the spring of 1944 the Army began work on the M4A3E2 or Jumbo. It was intended for use in attacking the German West Wall defenses. The Jumbo was a heavily armored version of the M4 and weighed 42 tons (as opposed to 31-34 tons normal weight). The additional weight was all armor. The front plate was 101 mm at 47 degrees for an effective thickness of 148 mm. The turret was 152 mm. front and sides with a 177 mm gun mantle.
Although the suspension was strengthened, the Jumbos suffered higher breakdown rates due to the weight increase. The Jumbo mounted the original 75 mm, gun, but some were modified in the field with the 76 mm gun. Only 254 Jumbos were produced.
The last major model of the M4 was the M4A3E8. The improvement of this model's was the horizontal volute suspension, which gave a smoother ride and allowed a wider track. The wider track helped greatly with mobility, especially over soft ground.
Thus in 1944 the U.S. introduced two new models of the M4, the Jumbo and the E8. In addition, the M-36 was introduced, giving the U.S. a 90 mm AT gun.
M-26 Pershing
The last important vehicle in the U.S. Army inventory was the M26 Pershing. Design for a replacement for the M4 started almost as soon as the design for the M4 was completed. From 1942 to 1944, there were several experimental models worked on by different design groups. They were the T-1/M-6, T-14, and T-20 through T-26. The T-1/M-6 went into production but was cancelled after about 40 were produced. Since the weight of the vehicle was about 60 tons, it was reasoned that two medium tanks could be shipped in place of one heavy tank. Shipping was always limited for the Allies, and this was enough to kill the project off. (The U.S. Army had only one motorized infantry division; it never saw combat as such since it required as many ships to transport as an armored division. No commander ever requested it, and it was converted back to regular infantry in 1945.)
While many of these designs ended up as improvements to the existing M4, none of these models were put into full production. The turret of the T73 did go into production as the one used to house the 76 mm gun for the M4, and the horizontal volute suspension of the M4A3E8 also came from the T-25.
In September of 1943 the Ordnance Department urged the production of 500 of the last model T75E1 and 500 of a heavier model the T26EL Both of these were heavy tanks mounting the 90 mm gun of the M36. This was opposed by the Armored Forces Board, who wanted a 90 mm gun M4, and by AGF who opposed giving tank units 90 mm guns for fear they would go tank hunting, a task assigned to tank destroyers. The Army Command, Armored Forces, and AGF continued to delay the M26.
Finally, limited procurement was finally approved in November of 1944. The first 20 M26 were ready in December, and Ordnance requested that they be shipped to Europe for combat testing. But the Army asked that they be sent to Armored Forces for testing. The German Ardennes Offensive caused the U.S. General Staff to intervene and the existing M26s were sent to Europe in early January 1945. Final production was about 1,430 M26s by the end of the war.
Conclusions
In 1940, General Chaffee made the correct decision that the M4 needed a 75 mm gun. That was probably the last timely decision made by an American. The failure to push for the 76 mm and 90 mm. sooner, lies with the overall structure of U.S. forces at the time. The request should have come from the European Theater Commander. But in 1943 the U.S. was only involved in fighting in Italy. Italy was not tank country, and the majority of the fighting was conducted by foot soldiers. It was not until after the invasion of Normandy that Eisenhower began asking for a replacement for the 75 mm. By then it was really too late.
The U.S. lagged behind Germany in tank design and production. The Americans designed the M4 in October of 1941 to meet conditions current at that time. However, by the time the Sherman design went into production in April of 1942, the Germans were designing the Tiger I, a far superior tank. The first Tigers rolled off the production line in August of '42, only four months after the Americans started the production of the M4, an inferior tank. In addition to the Tiger, the Germans had a clearly superior gun on the Panther. The Americans did not upgrade to a 76 mm. gun until January of 1944, while the Germans had an equivalent weapon two years sooner-the long 75 mm, which was in production for the Panther in November of 1942.
Given the fact that the U.S. produced the best aircraft, ships, and had semi-automatic rifles before the war, why was tank design so far behind? Part of the blame must fall on General McNair for advancing his pet project, the tank destroyer, at the expense of the tanks. McNair controlled the maneuvers that were a test of the policy of tank vs. anti- tank and ruled in favor of the tank destroyers. This probably cost the U.S. in the long run.
I do not wish to give the impression that the Sherman was poor tank; it was probably the most mechanically reliable tank in the war. The fact that it served around the world into the late sixties attests to the design. It is just that it could have been better. If the 76 mm gun had been adopted the first time around it could have been in the field by early 1943, not the middle of 1944.
Similarly, if the M-25s and M-26s had been put into production at the time of the first request they could have been ready by June of 1944. With a few companies of heavy tanks as a spearhead, the high price in lives that the U.S. Army paid to breakout from the beaches in July might have been less.
| Production of M3 and M4 Tanks | |||
|---|---|---|---|
| Model | Variation | Total Production | Dates |
| M3 | Weld hull | 4,924 | 6-41 to 8- 42 |
| M3A1 | Cast hull | 300 | 1-42 to 7- 42 |
| M3A2 | Weld hull | 12 | 1-42 to 3- 42 |
| M3A3 | M3A2 with Diesel | 322 | 3-42 to 12-42 |
| M3A4 | M3 with Chrysler multi-bank * | 109 | 6-42 to 8-42 |
| Total of all models M3s | 5,667 | - | |
| M4 | Weld hull, Radial engine, 75 mm | 8,306 | 7-42 to 1-44 |
| M4 | 105 mm howitzer | 1,641 | 2-44 to 3-45 |
| M4A1 | Cast hull, Radial engine, 75 mm | 7,839 | 2-42 to 12-43 |
| M4A1W | 76 mm | 3,246 | 1-44 to 7- 45 |
| M4A2 | Diesel engine, 75 mm. | 8,053 | 4- 42 to 5-44 |
| M4A2W | 76mm | 2,915 | 5-44 to 5- 45 |
| M4A3 | Ford V-8, 75 mm | 5,377 | 6-42 to 9-43 |
| M4A3W | 76mm | 4,542 | 3-44 to 4- 45 |
| M4A3W | 105mm | 3,039 | 5-44 to 6- 45 |
| M4A3E2 | Jumbo | 254 | 6-44 to 7- 44 |
| M4A4 | 75mm, Chrysler multi-bank * | 7,499 | 7-42 to 9-43 |
| M4A6 | Radial Diesel, 75 mm | 75 | 10-43 to 2- 44 |
| Recovery vehicles | 137 | - | |
| Total of all models of M4s | 53,103 | - | |
| M-10 | Based on M4A2 with Diesel | 4,993 | 9-42 to 12-43 |
| M-10A1 | Based on M4A3 with Ford V-8 | 1,713 | 10-42 to 12-43 |
| M-36 | Based on M4A3 | 1,413 | 4-44 to 7-45 |
| M-36B1 | M36 turret on M4A3 Hull | 187 | 10-44 to 12-44 |
| M-36B2 | Converted M-10A1 | 724 | 5- 45 to 9-45 |
| M26 | - | 1,430 | - |
* The Chrysler multi-bank was 5 six-cylinder automobile engines linked to a single crankshaft. It was used in both the M3A4 and the M4A4. Since the U.S. Army felt it was too complicated to be reliable, all of these were lend-leased to Great Britain or the USSR.
War Gaming
What does all this mean for the wargamer? For one thing, there are some interesting what ifs. Placing the M-26 turret on the M4A3E8 hull is probably the most interesting. These vehicles could have been available by the end of 1944.
My current tank destroyer units have M-18s, but the M-10 is much more flexible if you are doing different time periods. The M-10s served in North Africa, Sicily, Italy, France, and Germany. The bonus here is that with the purchase of M-36 turrets M10s convert instantly to M-36s. Also, the M4A3 late production (front armor at 47 degrees) can be converted to an M-36Bl with the M36 turret. This gives a little better armor than an M-36 and a nasty shock to the German player who is not looking closely and thinks they're M-4s.
The British Firefly is always nice to have; if you are doing Americans and having a hard time you can probably convert to British, Canadian, or Polish Armor and add one Firefly per company if you are doing June through August of 1944. The British also mounted the 17 pdr in their M-10s.
There are some restrictions. The U.S. did not use the M4A2 or M4A4. They also did not mix tanks with different engines in the same units (probably to battalion level). This means that you might have M4s and M4AIs together (both had the radial engine), although you will not have M4A3s with either. Also the radial engine was weaker than the diesel or the V-8 and only gets up to 21 mph as opposed to 25-26 mph for the others.
Bibliography
Hunnicut is the single best source of information on the Sherman. Including the data tables at the end, it is over 560 pages. If you need to know something, that's where you should start. Peter Gudgin's book is also worth mentioning. While it is mostly concerned with the Tiger tank it also discusses the problems with German production during the war. It discusses all of their early tanks, their research programs, and the problems and faults of their production.
Crow, Duncan and Robert J. Icks. Encyclopedia of Tanks,
Chartwell Books Inc., Secaucus NJ 1975.
Ellis, Chris and Peter Chamberlain. The Great Tanks,
Hamlyn, London 1975.
Farago, Ladislas. Patton: Ordeal and Triumph, Dell Publishing Co, 1963.
Forty, George. M4 Sherman, Blandford Press 1987.
Green, Constance, Harry Thomson and Peter Roots. The
Ordnance Department: Planning Munitions for War, Office
of the Chief of Military History, Department of the Army Washington, DC 1955.
Gudgin, Peter. The Tiger Tanks, Arms and Armour Press, London 1991.
Hogg, Ian V. Armour in Conflict, Janes, London 1980.
Hunnicut R. P. Sherman: A History of the American
Medium Tank, Presidio Press, Movato, CA. 1978.
Schreier, Konrak Jr. The Classic Sherman,
Grenadier Books, Canoga Park, CA. 1969.
Thomson, Harry and Lipa Mayo. The Ordnance
Department: Procurement and Supply, Office of the Chief of
Military History, Department of the Army Washington, DC 1960.
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