Monday 14 December 2020

Beefy Sherman

American light and medium tanks had distinctively well balanced characteristics in WWII. The Americans rarely went too far in the armour department, reasoning that the mobility of a tank is one of its most important characteristics. However, the idea of building a tank with improved protection was not alien to them. One of these tanks was the specialized M4A3E2 tank, the best protected medium tank of WWII. Even though few were made, the M4A3E2 fought actively and proved itself to be an effective weapon.

A thicker front

The Medium Tank M4 was one of the best tanks in the world at the time of its creation. It had superior power to weight ratio to the Pz.Kpfw.III and Pz.Kpfw.IV produced in 1942, its sloped armour protected it from 50 mm guns at medium distances, and its powerful 75 mm M3 gun turned out to even be able to penetrate the Tiger from the side at a range of a few hundred meters. The tank had its drawbacks. The armour was not the greatest (Soviet experiments showed that it was worse than Soviet armour), and there were also complaints regarding the tank's excessive size and sights.

One of the first attempts to improve protection of the differential housing implemented on the experimental Medium Tank T6.

Several of the M4's drawbacks were corrected during production. However, due to the increase in the calibers of German anti-tank artillery the M4's armour was no longer satisfactory by 1943. A modernization carried out in the second half of 1943 resulted in 64 mm thick front armour, but the slope was reduced. The sides were thickened to 38 mm. It was no longer possible to increase armour protection, as the load on the chassis increased, unevenly at that. This threatened to overload the front bogies and drastically reduce their lifespan.

Applique armour for the differential housing, July 1943.

Work to improve the armour of the Medium Tank M4 proceeded nevertheless. The differential housing was one of the most vulnerable parts of the tank. It was often hit, and so a lot of attention was paid to it. Various ways to improve its protection were tested, including a welded variant. Each solution had the same drawback: difficulty of production. It wasn't enough to improve the tank's protection, it had to be as easy to produce as it was before.

The modernized hull. You can see the new differential housing with a slope matching the upper front plate.

The first step to improving the differential housing was to produce it in one piece (initially it was made from 3 sections). In May of 1943 the Aberdeen Proving Grounds tested a number of applique plates in May of 1943, none of which were used in production. The solution was found during the aforementioned modernization of the hull. A new differential housing was made that matched the slope of the upper front plate. Its thickness was variable from 51 to 108 mm. The protection grew as a result, although it still was not impervious to 75 mm shells. However, any solution offered was still not entirely satisfactory.

A model of improved hull and turret front armour, February 1944.

Creation of removable armour dating February 1944 was another interesting development. The idea was to produce special applique plates in factories that would improve the hull and turret armour. Chrysler presented a wooden model of the armour package that covered the front of the hull, front of the turret, the gun mantlet, and partially the sides of the turret. The applique armour program was cancelled as quickly as it began. The brass started to suspect the cost that this armour would come at. The extra armour would do nothing to improve the lifespan of the suspension. However, less than a year later similar solutions were common on the front lines. Everyone wanted to live, and commanders often ignored (or even initiated) installation of improvised armour. Some of these packages were even heavier than Chrysler's solution. Interestingly enough, these conversions were triggered by a production vehicle with improved armour.

Assault Tank, American style

Development of the Assault Tank T14 came before any effort to improve the armour of existing tanks. This vehicle was ordered by the British and was essentially a thoroughly reworked Medium Tank M4. Even though the hull and turret designs were quite good, the Assault Tank T14 was doomed to failure. The vehicle was less reliable than its predecessor, especially when it came to the suspension. The mass reached 42.6 tons, much more than a Medium Tank M4. Changing the suspension didn't help.

A Medium Tank M4A3 loaded to 37.5 tons.

Trials continued until November of 1943, when the Assault Tank T14 was judged a failure. However, the idea of creating a more mobile equivalent of an infantry tank was a good one. The creation of a new tank like the T14 or raising the mass so high were both off the table. The American assault tank idea was faster and simpler. The Medium Tank M4A3 was taken as the basis, as it had the most powerful engine. The turret, hull front, and hull sides were thickened. Calculations showed that the chassis could take a weight of 37.5 tons if the suspension was reinforced appropriately. This gave an armour reserve of 7.2 tons. 

Side view of the Medium Tank M4A3E2. The Medium Tank M4A3(75)W was taken as the basis.

To test this theory, General Motors was instructed to convert one Medium Tank M4A3 on December 17th, 1943. The tank was loaded with steel plates welded onto the front and sides of the hull as well as the gun mantlet. Extended end connectors were added to the T48 tracks to compensate for the weight. The converted tank drove for 800 km with no serious defects. The possibility of building an assault tank on the chassis of an existing vehicle was confirmed.

There were no prototypes with the M4A3E2, production started right away.

As a result, work on the assault tank and the aforementioned applique armour package kicked off. The latter was quickly killed off due to the issues with overloading the front suspension bogeys. As for the assault tank, preliminary blueprints were ready by March 2nd, 1944. The Ordnance Committee recommended accepting the tank into service as the Tank, Medium, M4A3E2. A batch of 254 vehicles was aldo discussed. 

The tank was much better protected thanks to stronger front armour.

When the M4A3E2 was approved the Fisher Tank Arsenal in Detroit started building a new variant of the M4A3. This tank was called M4A3(75)W, the letter W indicated that the tank had a wet ammo rack. These tanks had modernized hulls with the new front section and thicker differential housing. The weight of the tank increased to 31.6 tons. This reduced the amount of extra armour it could carry, although the weight limit was raised to 38 tons. In addition, Fisher started building another new tank in March of 1944, the M4A3(76)W, which had a turret from the T23 tank. The tank itself did not see service, but its turret came in handy, since it had the same turret ring as the M4. It was installed on the M4A3 with minimal changes, giving a roomier fighting compartment and a more powerful weapon. It was decided to use this turret on the assault tank.

The upper sides of the tank were also strengthened.

Contract T-9724 for production of the Medium Tank M4A3E2 was logically given to the Fisher Tank Arsenal. The tank was accepted into production without a prototype. The design was based on the M4A3(75)W with the M4A3(76)W turret, although it still had a 75 mm gun. The only difference was the armour. The upper front plate was 102 mm thick, but it was not a monolithic plate. A 38 mm thick plate was welded on top of the stock 64 mm one. The same thing happened to the sides, giving a total thickness of 76 mm. Extra armour was only added to the top, there was no protection for the suspension like on the Assault Tank T14. The cast differential cover was from 114 to 140 mm thick. No other medium tank had this much armour in WW2.

The turret armour was also considerably thicker: 152 mm all around.

The turret was more complicated. Unlike the hull, it wasn't possible to just weld more armour on it, so it was designed from scratch. It was similar to the T23 tank turret (know by its part number as 7054355). Unlike early turrets of this type, the commander's cupola of the Medium Tank M4 used as the loader's hatch was replaced with a new oval hatch. Instead, the loader regained his rotating periscope. The M4A3E2 turret (part number 7067400) was wider due to its protection. The front, sides, and rear were all 152 mm thick. The thickest part was the gun mantlet at 178 mm. The 75 mm gun was installed int he M62 gun mount, initially designed for the 76 mm M1 gun.

The new gun mount was indexed T110, although there weren't many changes compared to the M62. This came in handy later. Two factories received the contract for turrets: Union Steel and Ordnance Steel Foundry. The turret casting varied between the two: Ordnance Steel Foundry made turrets with sharp and clearly defined lower edges, while Union Steel had smoother edges. A number of later production tanks also received smooth T51 tracks instead of T48 tracks with chevrons.

The first production tank was changed several times during trials.

The M4A3E2 weighed 38.1 tons instead of the original 37.5. This of course had an impact on its mobility. The gear ratio was changed, reducing its top speed to 35 kph. This was a little less than the Assault Tank T14, but everyone understood that this tank was not meant for cavalry charges. The result was a tank with comparable protection to the Churchill VII with superior protection in the front. However, the Ordnance Department had not reached a consensus regarding the fate of this tank and decided to see what comes out of the initial batch before making decisions regarding continued production.

Results of firing at the first experimental tank. Even though 90 mm shells were used, most of them did not result in penetration.

Work on contract T-9724 began in May of 1944. Fisher Tank Arsenal delivered 40 tanks in the first month of production, 110 in June, and the remaining 104 in July. The tanks had serial numbers 50326-50579 and registration numbers U.S.A. 3082923-3083176. The first production tank was sent to Chrysler's tank laboratory on May 19th for trials. They showed that the experiments with the loaded down tank performed in late 1943 and early 1944 were correct. Only one suspension spring broke during a 640 km drive. In general, the tank's reliability was deemed to be on par with the lighter M4A3(75)W. However, the driver had to be more careful off-road in order to preserve the front bogeys. This tank was later sent to Fort Knox, where it also successfully went through trials.

The gun mantlet was the thickest part of the tank, although on the front lines hits to the gun sight opening were not uncommon.

The first penetration trials were held in May of 1944 and then again in August-September of 1944, when production already ended. It was fired at with 90 mm guns that were more powerful than the 88 mm guns it was originally designed to protect against, perhaps this was an imitation of the 88 mm Pak L/71 gun, the most powerful anti-tank gun the German had at the time. The armour was not meant for this, although there were still cases of non-penetration at 900 meters. The gun mantlet was the toughest part. It was not penetrated by an M82 shell even at a range of 550 meters. Trials showed that the protection was very respectable, especially compared to that of other American tanks.

"Send more, lots more!"

All but 4 tanks (including the first one produced) of the 254 built were sent to the front. Initially the plan was to send 252 overseas, but on September 10th, 1944, the number was reduced by 2. The tank ended up on the front lines very quickly, as the army desperately needed something like it. The 1st Army was the first to get vehicles of this type. On October 14th, 1944, they were issued to the 743rd, 745th, and 746th Tank Battalions. 100 tanks of this type were issued in the 1st Army in total. M4A3E2 tanks began arriving in the 3rd Army on November 22nd, including the 702nd, 712th, 735th, 737th, and 761st Tank Battalions, as well as the 10th Armored Division. 60 tanks were issued in the 3rd Army in all. Finally, as of November 27th the 9th Army began receiving the thickly armoured tanks. They were first issued to the 747th Tank Battalion. 90 were issued to the 9th Army in total.

M4A3E2 tanks arriving in France.

The 6th Armored Division was among the units of the 3rd Army that received the tank. This unit is responsible for the nickname attached to the M4A3E2 after the war. One tank from B Company fell sideways into a wide ravine in Saint-Jean-Rohrbach on November 22nd, 1944. This tank was photographed, and the photographer titled it "Jumbo M-4 Tank". Jumbo was the name given to the first famous circus elephant. It's hard to say why the photographer chose this title, perhaps the tank lying on its side reminded him of the elephant who died after being hit by a train. Either way, the nickname Jumbo started here. It was not used in any official documents, in all likelihood it was only used after the war.

This photograph linked the name Jumbo to this tank.

As it often happens with new vehicles, the debut of the M4A3E2 was not entirely successful. One of the first units to use this tank was the 743rd Tank Battalion in support of the 30th Infantry Division. The battalion crossed the border between the Netherlands and Germany in November of 1944. The first total loss happened here. On November 16th, during the Battle for Würselen, one tank was destroyed by a hit from a Panzerfaust. On November 22nd the battalion fought at Neu-Lohn where two more tanks were lost. One tank was hit no less than 10 times, one of which was fatal. The shell hit the opening of the telescopic sight, penetrating the mantlet and killing the gunner. Two more crewmen were wounded and a fire started, which eventually blew off the tank's turret. The second tank was also hit multiple times, with a fatal penetration in the side.

About two thirds of the total number of tanks built were actively used in battle by the end of 1944.

As of December 3rd, total losses of M4A3E2 tanks numbered 10. 154 tanks arrived (129 had been issued), 74 were on the way, and 12 awaited shipment in the US. Despite the losses, these tanks were highly judged. The thick front armour came in handy in situations when the regular Medium Tank M4 would have no chance of survival. Nearly all units that used the M4A3E2 demanded more tanks of this type. Of course, the increase in protection came at the cost of reliability. The amount of complaints regarding the suspension and transmission was higher than in the case of ordinary tanks. However, the improved armour was very important. It turned out that this infantry support tank was also in demand with tank units. Since they could survive a hit from most enemy shells, they were often used at the front of tank columns. The M4A3E2 tank gave American tankers a counter to German 88 mm guns.

Additional front armour installed in the 743rd Tank Battalion.

Since there were few M4A3E2 tanks built, they were often delivered in small numbers, sometimes a unit would get just 3-4 of them. Nevertheless, the success of the assault tank was obvious by early 1945. However, there were some issues. The idea that this tank would be used for infantry support was incorrect. This tank was also in demand by tank divisions. For instance, the 4th Armored had 20 of them, the largest number of M4A3E2 tanks in any division. The idea that a 75 mm gun would be enough was rejected and the tankers required a 76 mm M1 gun. This requirement was described in a letter from Eisenhower to the British War Department sent on January 31st, 1945. He requested urgent delivery of a maximum amount of the new M4A3E2 tank, with the only required change being the installation of a 76 mm gun. Later there was also the request for the HVSS suspension that could carry greater loads.

The most famous photo of the Medium Tank M4A3E2. This tank was the first to arrive in besieged Bastogne.

The American war machine did not work as expected. The idea of even greater improvement in armament arose, which led to the installation of a T26E3 turret on the M4A3E2 hull. This idea was later implemented in a prototype (albeit on an M4A3(75)W chassis), but the situation changed by then. The Heavy Tank T26E5, a Heavy Tank T26E3 with more armour, was developed. The result was suboptimal. Instead of production of the improved M4A3E2 the Americans developed a whole new tank. Obviously, the T26E5 was too late to fight in addition to showing suspension issues.

Only 61 tanks were lost over the course of more than half a year of active combat.

The lack of American agility can be seen from the equipment of the M4A3E2. Even though units requested that tanks should not have dust shields, they were installed until the very end. The dust shields were removed in the field almost immediately, and so photos of the vehicles with shields installed are rare. The lack of M4A3E2 tanks was partially compensated by field workshops. It was clear that the additional armour was working, but no new M4A3E2s were expected. Units started to thicken the armour on ordinary tanks. No thought was given to how the suspension or transmission would hand the weight, protection was of utmost importance. Even the Medium Tank M4A3E2 received additional protection in some units. Sandbags to protect from German anti-tank rockets were installed on the front armour. Of course, the sandbags reduced the lifespan of the suspension, but everyone wanted to live, and these kinds of improvements were not forbidden by commanders.

Despite some issues, the M4A3E2 met a warm welcome in units. The idea to radically improve front armour was a good one, but American industry didn't capitalize on its success.

Thanks to field workshops, the issue with armament was also partially solved. A system to rearm tanks with the 75 mm M3 gun to the 76 mm M1 was developed in February of 1945. Tanks with ordinary turrets were not rearmed for the same reason as in 1943, their turrets were too cramped. However, re-arming the M4A3E2 was approved. As mentioned above, the T110 gun mount was a slightly altered M62 gun mount created for the 76 mm M1, so there were no issues with changing it. About 100 tanks received 76 mm guns. Depending on the workshop that performed the replacement, the gun mantlet was different. Some of them left it as is, some of them cut off a part. Interestingly enough, a number of M4A1(75)W and M4A3(75)W received 76 mm guns in the late 1940s. These tanks were called M4A1E4 and M4A3E4.

About 100 M4A3E2 tanks received 76 mm guns, which improved their effectiveness on the battlefield.

One number demonstrates the effectiveness of the assault tank idea. From November of 1944 to May of 1945 only 61 Medium Tanks M4A3E2 were irreparably lost, a little more than a fifth. Recall that these tanks were often at the vanguard of attacking units. One can only marvel at the short-sightedness of American commanders who elected to waste time on prototypes that ended up being late for the war rather than resume production of a successful vehicle. As for the final fate of the M4A3E2, they did not fight after WWII. About 100 tanks were modernized in the early 1950s, but starting in 1957 they were written off. Fewer than 10 tanks survive to this day, including the famous Cobra King, the first to reach Bastogne during the Ardennes counteroffensive.

1 comment:

  1. When Cobra King was at Fort Knox they had a little display for it inside of the armor museum there. The display included some of the melted and fused 30-06 cartridges that had cooked off when the tank was knocked out and later burned.

    Unfortunately they never did get it on display before they closed up the museum for its planned relocation.