WW2 US Heavy Tanks

Assault Tank M4A3E2 Jumbo

United States of America (1944)
Assault Tank – 254 Built

In early 1944, the United States Army decided that they needed an up-armored version of a medium tank for an assault role for the upcoming operations in the European Theatre of Operations (ETO). However, they had rejected previous plans for such a vehicle, and time was short. As the new T26E1 would not be ready in time and previous designs had been totally unsuitable for the task, the decision was made to modify the standard US Army medium tank of the time, the M4A3 Sherman.
The vehicle became the M4A3E2 Assault tank or Sherman Jumbo. With only 254 built, it represented less than 1% of the total build numbers for the M4. However, it’s iconic profile left a lasting image that is probably one the most easily recognized M4 variants.
It should be noted at this point that the name ‘Jumbo’ doesn’t appear in any wartime documentation and is almost certainly a post-war nickname, quite possibly created by a model company.
The only running Jumbo, restored by Jacques Littlefield and now operated by the Collings Foundation - Source: Auctions America
One of the only two running Jumbos, restored by Jacques Littlefield and now operated by the Collings Foundation – Source: Auctions America


In February 1942, the British tank mission in the United States approached the US War Department with the idea of developing a heavy version of the soon to be produced M4 to meet the expected requirement for assaulting fixed enemy defensive lines. It’s likely that the British plan was to ask the Americans to cast a heavier version of the M4A1 by increasing the casting thickness up to 3 ½” (89 mm) on the glacis (front upper hull plate) and 3” (76 mm) on the sponsons (side upper hull plates).
Although this early plan came to nothing, the US Ordnance Department didn’t entirely forget about the idea and on 17th December 1943, the General Motors Proving Ground was directed to test an M4A3 with additional loading to a weight of 82,600 lbs (37466 kg). After 500 miles, it was found that “no abnormal failures were encountered. It, therefore, appears feasible to convert a medium tank to an assault tank with a weight of 82,600 lbs. If only limited operation is to be encountered.” This was therefore intended as a vehicle to be used on an as-needed basis and not for long periods of time or distance.
The M4A3 test tank with ballast fitted on 18th January 1944.
The M4A3 test tank with ballast fitted on 18th January 1944. The recently developed extended end connectors were fitted and helped to reduce the ground pressure even with all the additional weight. These extended connectors replaced the standard connectors that were used to join the individual track shoes together and added extra width to the track to disperse the weight of the vehicle. They were often called ‘grousers’.
Meanwhile, the Armored Fighting Vehicles and Weapons section (AFV&W) of the US Army European HQ put in an urgent request in January 1944 for 250 heavy tanks for the upcoming campaign in Europe. The request was based on the need for a tank to breach the Siegfried line. The following month, the Development Division of the US Army Ground Forces (AGF) agreed, but as the new T26E2 heavy tank was not expected until the following year, it was recommended that an expedient design should be based on an up-armored M4A3 medium tank. An alternative was offered by the Ordnance department, which proposed the old M6 heavy tank be modified to fulfill the role. The Ground Forces opposed this option because of the many problems of the M6 that were exposed during trials.
In March 1944, all parties agreed that the best solution was the up-armored M4 assault tank. On 2nd March, the Ordnance Technical Committee recommended that “the M4A3 with heavier armor be designated Medium Tank M4A3E2.” An order for 250 vehicles with 4 pilot vehicles was recommended and on 23rd March the order was approved. They were to be available to the army by August 1944. The contract was awarded to the Fisher Body Corporation in Detroit.
In an unusual move, Fisher was notified in late March that “in order to expedite delivery of the M4A3E2 Assault Tanks, certain requirements of applicable specifications will be waived for the total of 254 vehicles”. Put simply, the US Government trusted Fisher to do the job to the standard required without the need for the normal and rather time-consuming testing regime. This explains how the tank maintained its ‘E’ number designation. The letter ‘E’ stood for experimental and if the Ground Forces found the vehicle unfit for task, Fisher would still have been paid for all 254 ‘experimental’ vehicles which then would have remained in the US. As it was, all vehicles were provisionally accepted and 250 were authorized for overseas shipment at the end of May 1944.


The M4A3E2 was to have an additional 1 ½” (38 mm) of armor plate welded to the upper hull front and sides, taking the overall thickness to 4” (101 mm) on the front and 3” (76 mm) on the side. The rear upper hull and top were unchanged, as was the lower hull. To ensure a good weld the additional side armor was welded in two pieces with a 2” (50 mm) gap in a vertical center line filled with weld. The additional plate had a keyhole cut into it to allow fitting over the existing bow machine gun ball mount. The standard beading that the dust cover fitted to was then welded to the new plate. The normal lights and sirens were not fitted. The 75 mm gun travel lock was fitted on 3” (76 mm) spacers.
Union Steel foundry was subcontracted to cast a heavier final drive assembly cover. The new casting was 3000 lbs (1360 kg) heavier than the standard and had a thickness that varied from 4” (101 mm) to a maximum of 5 ½” (139 mm). The new casting had to have a substantial ridge along the upper edge to allow for the fitting and bolting to the upper hull.
Pressed Steel Car was subcontracted to assemble and finish the turrets and gun mounts with the actual casting being done by Union Steel and Ordnance Steel foundries. The turret was based on the T23 76 mm turret with a similar internal layout and a full basket, but the pistol port was eliminated. The thickness was approx 6” (152 mm) all around but it did reduce to 2 ½” (63mm) at the rear below the bulge.
The 75 mm gun was installed in a modified M62 Gun Mount normally used for the 76 mm gun. An additional 5” (127 mm) of armor plate were added to the M62’s original 2” (50 mm) cast gun shield, creating a huge mantlet covering nearly ¾ of the turret front. This modified mount was designated ‘Combination Gun Mount T110’. The completed turret weighed in at an impressive 20,510 lbs (9303 kg), roughly 5000 lbs (2267 kg) heavier than the original T23 turret casting. The gun shield alone was 1100 lbs (498 kg) heavier than the standard shield.
Combat load included 104 75 mm rounds for the main gun, 600 rounds for the .50 caliber, 6250 rounds for the .30 caliber, 900 rounds of .45 caliber, 18 hand grenades and 18 2” smoke rounds.
To allow for all the additional weight of the tank, extended end connectors were fitted as standard to the tracks. These increased the ground contact by nearly 10% and kept ground pressure to a fairly reasonable 14.2 psi, compared with 13.7 psi for a standard M4A3 without extended end connectors. Although the original Ford GAA V8 powerplant was retained, the final drive ratio was increased to 3.36:1. This reduced the top speed to 22 mph (35 km/h), but the tank maintained reasonable acceleration even though it now weighed 84000 lbs (38101 kg). It could climb a 60% slope, cross a 7’6” (2286 mm) trench, climb a 24” (609 mm) vertical wall and ford 36” (914 mm) of water.
Fisher completed production in July 1944.

cobra King forst in Bastogne poster
Xmas special 2019 David B. Poster: Support Tank Encyclopedia and get the most accurate depiction of M4A3E2 Cobra King “First in Bastogne”. See below for the complete history


On the 8th June, tank 50326 was shipped to the Chrysler Tank Arsenal Proving Ground in Detroit for endurance trials. After some 400 miles which resulted in one broken spring it was however noted that the same “low milage failures had been experienced with standard weight vehicles”. It was apparent though that the additional weight of the Jumbo was seriously taxing the standard vertical volute suspension of the M4.

The difference can be seen between the three different bogie sets in the picture taken at Aberdeen. The middle and front bogies are clearly overloaded with the front set arms almost horizontal. As a result, the following order was issued “One thing that users must realise is that, in rough cross-country operation, the front volute springs will fail if permitted to ‘bottom’ violently”.
After the endurance test, tank 50326 was sent to Aberdeen Proving Ground (APG) for ballistic testing. As these tests took place in September 1944 some time after the M4A3E2 was released for overseas shipment the tests were for “information purposes only”. The tank was tested to destruction.

Operational service

The first vehicles arrived in the New York port on the 14th of August 1944. On the 29th, the 12th Army Group was informed by the War Dept that 250 M4A3E2 Assault tanks had been released and would be in the ETO in September. On the 1st September, the 3rd Armored Division put in a request for 150 M4A3E2s from 12th Army Group. The first 128 Jumbos arrived in France via Cherbourg on the 22nd September 1944.
Full records of exactly how the Jumbos were issued are difficult to identify as the tank were often only recorded as ‘Medium Tank M4A3’ with no distinction between a standard M4A3 and an M4A3E2. But partial records have been traced although some do seem to conflict. The first thirty six tanks were issued to the US First Army on the 14th October and were then issued to individual tank battalions. Fifteen to the 743rd, fifteen to the 745th and six to the 746th. On the 18th October, Normandy beach depots recorded having seventeen on hand, twenty four released to Armies and nineteen on route to Third Army. By the 24th October Army allocations for delivery had been confirmed as:
First Army – 105 M4A3E2 Jumbos
Third Army – 90 M4A3E2 Jumbos
Ninth Army – 60 M4A3E2 Jumbos
Clearly someone at 12th Army Group needed a little extra work on their basic maths!
The last recorded delivery was on the 9th November when 746th Tank Battalion of the First Army was issued a further nine Jumbo’s.
The tanks were well received and the advantages of the additional armor were quickly appreciated. Jumbos were chosen to be the standard point tank any time advances were made with opposition expected.
A 76mm armed Jumbo of the 3rd Armoured Division, Cologne, 6th March 1945.
A 76 mm armed Jumbo of the 3rd Armoured Division, Cologne, 6th March 1945.
Crews did still feel the need to add more armor and sandbags were a common addition to the glacis and in a few cases concrete was used. The additional weight of 4”-6” (101-152 mm) of concrete right on the nose of the tank must have made it a very difficult proposition to drive. The front bogie was almost certainly beyond its maximum weight capacity by that point and a mechanical failure on the front bogies was most likely a case of when, not if.
M4A3E2 of 743rd Tank Btn, Altdorf, 27th November 1944. Sandbags covered with hessian and possible turf on the glacis.
M4A3E2 of 743rd Tank Btn, Altdorf, 27th November 1944. Sandbags covered with hessian and possible turf on the glacis.
M4A3E2 with concrete applique on glacis, date and location unknown (frame from a US Army Signal Corp film
M4A3E2 with concrete applique on glacis, date and location unknown (frame from a US Army Signal Corp film)
Because of the nature of their employment, the Jumbos suffered heavy losses. The 4th Armoured Division alone recorded 24 M4A3E2s lost in action in their after action report at the end of the war. Twenty four lost in one division may not sound like a lot, but when it is considered that nearly 10% of the total production run of the vehicle was lost in one division it shows they clearly bore the brunt of the fighting wherever they were present. Even with all the additional armor, Jumbos were still as vulnerable to mines as any other tank (minefields often covered approach routes to German positions) and concentrated anti-tank gun fire.
This Jumbo of 743rd Tank Battalion was knocked out on 22nd November 1944 near Lohn, Germany.
This Jumbo of 743rd Tank Battalion was knocked out on 22nd November 1944 near Lohn, Germany. It was hit by four 88 mm rounds from an anti-tank gun 800 yds (730 m) away. One bounced off the glacis plate and two off the manlet before the fourth actually penetrated through the gunners telescope opening (chalked ‘9’ by Divisional Intelligence staff).
Another Jumbo of 743rd Tank Battalion also knocked out in the same operation.
Another Jumbo of 743rd Tank Battalion also knocked out in the same operation. This one was disabled by a ‘friendly’ mine and abandoned by its crew with no casualties. After it was abandoned the Germans concentrated anti-tank fire on it to ensure it wasn’t recoverable.
During February 1945, approximately 100 M4A3E2s were upgunned to 76 mm using guns recovered from knocked out 76 mm armed M4s and normal supply stocks. This upgrade was a fairly straight forward field modification, as the combination gun mount was originally designed for this gun. The more complicated part of the conversion was the modification of the main gun ammunition stowage. This required removing the turret and the fitting of 76 mm racks in place of the shorter 75 mm racks. These replacement racks were then secured in place with a series of fabricated welded braces. Records indicate that conversion took 75 man hours per tank.
Out of the 250 sent to Europe, today there are believed to be eight complete survivors and one further hull and turret. Of the four test vehicles that remained in the States, none survived. Of these four, only one cannot be positively accounted for. The first was destroyed during impact testing as stated above. The second was used as a post war test bed for two different flame thrower tanks and was then used as a range target at Ft Knox. The third was sent to the Aberdeen Proving Grounds for additional testing. Its disposition is unknown but it was likely scrapped.
As for the fourth, it was last reported in a depot in Pennsylvania in 1945. It may still be somewhere awaiting discovery but in all likelihood it was also scrapped.
This up armored M4A3 (76) HVSS of the 4th Armoured Division shows the addition of armor plate to the glacis and turret.
This up armored M4A3 (76) HVSS of the 4th Armoured Division shows the addition of armor plate to the glacis and turret.
Alongside the up gunning of the Jumbo’s, the 12th Army Group commissioned the building of what became known as Field Expedient Jumbos. These were M4A3 (76) HVSS (often called M4A3E8s or Easy Eights) with additional armor welded to the glacis and turret. These tanks often achieved very near levels of armor to the original Jumbos. The additional armor was scavenged from wrecked tanks. Other M4s and Panthers were preferable. Entire glacis plates from wrecked M4s could be cut out and welded to the new vehicle without needing to move gun travel locks or cutting new apertures for the bow machine-gun. Much of this work was carried out by three civilian factories with an allowance of 85 man hours per vehicle.
A report from the 6th Armoured Division noted the success of these Expedient Jumbo’s. ‘A recently modified M4A3E8 took a direct hit from a German 75 mm shell with the only resulting damage being the complete separation of the middle section of additional armour from the hull. The tank continued in the action and succeeded in “knocking out” the opposing vehicle.The crew whose lives were saved by this additional protection were loud in their praise of this modification.

M4A3E2 Houffalize jan 1945
M4A3E2 “Jumbo” from the 33rd Battalion, 3rd US Armored Division, Houffalize, Belgium, January 1945.
Cobra King Sherman M4A3E2
M4A3E2 Jumbo “Cobra King” with the “First in Bastogne” inscription, probably the most famous Jumbo of the entire 4th Armored Division.

M4A3E2(76)W jan 1945
M4A3E2(76) Jumbo from the 37th Tank Battalion, 4th Armored Division, Alez, Germany, March 1945.

Colonel Creighton Abrams
Colonel Creighton Abrams’ “Thunderbolt VII” and his famous personal insignia, Horazdovice, May 1945. This vehicle was a prime example of a Field Expedient Jumbo, being an Easy Eight with added armor.

Cobra King

Without doubt the most famous of all the Jumbos was named ‘Cobra King’, the first tank into Bastogne in Belgium, the vital crossroads town at the centre of the fighting during the Battle of the Bulge.
Cobra King was issued to 37th Tank Battalion of the 4th Armoured Division on the 24th or 25th of October 1944 and was assigned as the company commander’s vehicle of Company C. Much detail of Cobra Kings war service is difficult to confirm with absolute certainty but some of it is as follows.
From the time of its issue to its loss near the end of the war, Company C had five commanding officers who were all therefore Cobra King’s commanders.
July 1944 – 23rd November 1944, Richard Lamison
23rd November – 23rd December, Charles Trover (Trover was killed in action 23/12/44)
23rd December – 12 Januar 1945, Charles P. Boggess
12th January – (?), George Tiegs
(?) – 28th March 1945, William Nutto
Before the Battle of the Bulge details, of Cobra King’s actions are difficult to confirm. A well known one is on the 7th November outside Fontany, France when during an attack Cobra King took a hit to the final drive assembly that disabled the tank and left it with a permanent battle scar.

The splash damage left from the penetration of the final drive assembly - Picture: Don Moriarty
The splash damage left from the penetration of the final drive assembly – Picture: Don Moriarty
During the German winter offensive, the Battle of the Bulge, the important crossroads town of Bastogne, Belgium had been cut off and surrounded by German forces. Patton’s Third Army was tasked with trying to break through the German lines in the south with the 4th Armored Division as the main spearhead of this counterattack. On December 26, 1944, Lt. Boggess, commander of Cobra King, was fighting his way on the road from Assenois, Belgium to Bastogne. The following passage is from an article written by Charles Lemons, former curator of the Patton Museum.
Cobra King was way ahead of the rest of the column and had just destroyed a German bunker along the road when Boggess spotted several uniformed figures in the woods near the bunker. They wore the uniforms of U.S. soldiers, but knowing how Germans were disguising themselves as Americans, he maintained a wary eye. He shouted to the figures. After no response, he called out again and one man approached the tank. “I’m Lieutenant Webster of the 326th Engineers, 101st Airborne Division. Glad to see you.” With that meeting at 4:50 p.m. on December 26, 1944, Patton’s Third Army had broken through the German lines surrounding Bastogne
Cobra King
Cobra King
While records of the rest of the crew are not so complete the crew during the Battle of the Bulge is known.
Gunner, Milton B. Dickerman
Loader, James G. Murphy
Driver, Hubert J.J. Smith
Co-Driver, Harald D. Hafner
Cobra King was one of the Jumbos to receive a 76 mm gun upgrade and it’s coaxial machine-gun was also upgraded to a .50 cal (12.7 mm) in early 1945. The next part of Cobra Kings known service followed in March. More from Charles Lemons article.
After doing more research and discovering a post-war photo of an M4A3E2 Jumbo at a repair depot in Lager Hammelburg that had matching characteristics of Cobra King, the theory was presented that this was Cobra King and that it had participated in “Operation Hammelburg” the controversial mission which was personally ordered by Third Army commander General George S. Patton.
The operation took place on March 26-28, 1945 with the official purpose of liberating a prisoner of war camp, OFLAG XIII-B, near Hammelburg, Germany. But unofficially, it’s purpose was to free Patton’s son-in-law, Lieutenant Colonel John Waters, who was taken prisoner at Kasserine Pass, Tunisia, in 1943.
A small task force comprised of men and vehicles from the 37th Tank Battalion and 10th Armored Infantry Battalion commanded by Captain Abraham J. Baum, was formed. Task Force Baum consisted of M4A3 Shermans, M5A1 Stuarts, M4/105 Shermans, Jeeps and halftracks. The total strength was 314 men and 57 vehicles.
The task force fought through German lines with serious losses and reached Hammelburg and liberated the camp, but Patton’s son-in-law was wounded and had to be left behind. Ultimately, the entire operation turned into a total failure when German forces in the area eventually overwhelmed the small task force, destroying or capturing all vehicles and capturing Baum and almost all of his men and the liberated POWs.
Since Company C of the 37th Tank Battalion was in this raid, it leads to the question – did Cobra King participate in the ill-fated Hammelburg mission? In the book RAID!: The Untold Story of Patton’s Secret Mission by Richard Baron, Major Abe Baum and Richard Goldhurst, Baum stated that a tank named “Cobra King” commanded by Lt. Nutto was knocked out and abandoned on March 27, 1944 as it approached Hammelburg. But some historians have discounted this entry citing that the need for speed was essential on this mission and that a heavy, slow-moving Jumbo would be a hindrance.
Through these observations of Cobra King and research, then Patton Museum curator Charles Lemons proposed at the time the following:
“Cobra King is slowly revealing its secrets. The Patton Museum staff and volunteers have been brain-storming over the implications of what we have been finding. We all agree that this is “Cobra King” – no doubts what-so-ever. What the big question has been – what happened to the tank after December 26, 1944.”
“We can safely state that the vehicle remained in the 4th Armored Division – and remained as the command tank for Company C until its demise in combat. Yes, in combat – in fact the information we have indicates that the vehicle met its end in March of 1945. We firmly believe that Cobra King was lost with the rest of Company C, 37th Tank Battalion, and Task Force Baum, on the raid on Hammelburg.”
“Reminiscences from then Captain Baum, as written in the book “RAID!”, place Cobra King at the assault on Lager Hammelburg, where it was hit and put out of action. Unfortunately, Abe Baum does not note the damage.”
“However, what we have for Cobra King is a busted #3 road wheel assembly on the left side and evidence of a fire and subsequent small arms ammunition cook-off inside the BOG (bow gunner/co-driver) position. We have a vehicle that was recovered and taken to, of all places, Lager Hammelburg, where it was left in the yard until the mid-1950s.”
Further research by Don Moriarty has revealed that it is likely that Cobra King was actually hit by a Panzerfaust as the convoy was preparing to leave the camp not on the approach as originally thought. It is likely that this was the cause of the damage to the number three left side bogie station. The internal fire is not now thought to have happened at the time of the raid. As there was no main gun ammunition in the tank at the time of the fire and only machine-gun ammunition, it is believed that the Germans attempted to destroy Cobra King by torching her as the 14th Armoured Division approached Hammelburg in April 1945 to prevent it falling back into US hands in an operational condition.
“Further, C Company was only informed less than a day before the action, having been selected because it had the most tanks of the battalion. No commander would have abandoned one of his strongest vehicles – a Jumbo with a 76 mm main gun and .50 caliber coax – nor could he abandon his own command vehicle. Interviews with Brigadier General Jimmie Leach, B Company Commander, 37th Tank Battalion, show that even when in a hurry the tanks rarely traveled faster than 15 mph to avoid losing the infantry support, so a marginally slower vehicle wouldn’t have mattered.”
“Hammelburg was in the Seventh Army zone of control and 4th Armored Division, under Third Army, never came within 40 miles, with the exception of Task Force Baum. So how would a 4th Armored Division vehicle (Cobra King) end up in a Seventh Army repair facility?”
After the war, Cobra King became a monument tank, put on display at various American bases in Germany, Kitzingen (Harvey Barracks), Crailsheim (McKee Barracks), Erlangen (Ferris Barracks), & Vilseck (Rose Barracks) where it remained in obscurity, the wrong registration number painted on its side from one of its numerous repaints. In May 2001, Army Chaplain Keith Goode was checking out monument tanks while serving in Germany.
He was locating serial and registration numbers of Sherman tanks on U.S. Army bases. He passed the information onto the G104 Sherman interest group in the U.S. where member/historian Joe DeMarco confirmed that the tank was indeed the actual Cobra King.
After learning this information, another member of G104 stationed in Germany, Sgt. Brian Stigall of the Fifth Battalion, Seventh Air Defense Artillery and Steven Ruhnke, First Armored Division museum curator, paid Cobra King a visit and also confirmed the serial number and passed the information up the chain of command.
Along with other Army historians, including Patton Museum curator Charles Lemons, the identity of Cobra King was officially confirmed. Cobra King was then shipped to the United States and on to the Patton Museum’s workshops on July 9, 2009 for restoration.
Cobra King mid restoration - Source: Don Moriarty
Cobra King mid restoration – Source: Don Moriarty
At first, the plan was to restore the interior and exterior to the way Cobra King looked on December 26, 1944. However, this plan was altered due to findings in the interior of the tank. It was decided by the then Patton Museum director Len Dyer that the exterior of Cobra King would be restored to how she looked during the Battle of the Bulge, but that the interior would be left showing interior modifications to ammo storage and the damage sustained presumably at Hammelburg.
Four Patton Museum volunteers, Don Moriarty, Garry Redmon, Coleman Gusler and Robert Cartwright were selected to work with museum staff on the restoration along with other volunteers who also contributed to the restoration.
After a two-year exterior restoration, Cobra King was as finished as possible before she was shipped out to her new home at Fort Benning, Georgia in August 2011. – Patton Museum curator Charles Lemons
Cobra King on completion of restoration with the original 75mm gun returned - Picture Don Moriarty
Cobra King on completion of restoration with the original 75mm gun returned – Picture Don Moriarty
Today another Jumbo is in the town of Bastogne. It is not Cobra King, but it is painted in its markings in honor of this famous tank. It is however now missing its extended track end connectors. It is the only surviving Jumbo outside of the United States now that the real Cobra King has been returned to the States.
The only Jumbo in Europe, from the Belgian Tank Museum.
The only Jumbo in Europe, from the Belgian Tank Museum.


The overall effect of the E2 program was positive. It addressed the very real concerns of the crews that the M4 lacked the armor protection that enemy tanks had. It produced a tank that the Germans had a much harder time dealing with than they were used to. One thing unknown is the moral effect (if any) this had on German crews, as at normal combat ranges the Jumbos would have been difficult to distinguish from standard M4s and the effect of seeing your shots, that would normally disable or knock out a tank, having no effect cannot be a comforting sight!
An article by Adam Pawley

Sources & Links

Don Moriarty
Sherman: A History of the American Medium Tank, R.P. Hunnicutt
Armoured Thunderbolt, Steven Zaloga
Sherman Minutia
Charles R. Lemons
Garry Redmon
Armor for the Ages

M4A3E2 specifications

Dimensions 6.3 x 2.9 x 2.9 m
20’8” x 9’6” x 9’6”
Total weight, battle ready 38.1 tonnes (84,000 lbs)
Crew 5 (commander, driver, co-driver, gunner and loader)
Propulsion Ford GAA V8, 500 hp@2600 rpm
Speed (road) 35.4 km/h (22 mph)
Range approx 160 km (100 mi)
Armament 75 mm (2.95 in) Gun M3 or 76 mm (3 in) Gun M1 with 104 rounds
.50 (12.7 mm) HB M2 machine gun, 600 rounds
.30 (7.62 mm) M1919A4 machine-gun, 6250 rounds
Armor Maximum 177 mm (7”)

58 replies on “Assault Tank M4A3E2 Jumbo”

So it’s like a up armored Sherman, with more armor than a Tiger. But the Tiger’s gun could still pen it from a distance right? Also, was it a common thing to put extra spaced armor on Sherman’s? Even with this having 177mm of armor sloped? I understand for a normal Sherman, but why the E2?

I think that no matter how powerful any anti-tank gun is it hag to strike at the correct angle, but it is nice to know it was tough.

The program to upgun the Jumbo to 76mm produced the only U.S. tank, besides the Pershing, that was a real threat to heavier German tanks in terms of both firepower AND armor. The 76mm Jumbo was as historically significant as the earlier version, and the tanks final disposition and the fighting it was involved in was just as worthy of being commemorated and preserved.
And 76mm Jumbo tanks seem to be rare themselves. Frankly, they should have left the tank in 76mm form and restored it that way. The choice to regun it to 75mm, creating an unusual and historically inaccurate “Frankenstein” of a 75mm E2 tank with late war mods was a bizarre one indeed. They should have rethought that one. I know lots of buffs are in love with the Bulge and all…..lots of other fighting happened in the war and it was just as important historically.

The Jumbo was initially designed as an assault tank up against fortified positions. The 75mm gun is actually better suited for this role.

well you see since in today’s world people sometimes mistake a M4A3 and M4A3E2 and if people today make this mistake so did the Germans did but then if a King Tiger (Tiger II) and a Jumbo Sherman came across each other in close quarters combat the King Tiger would win the fight because of its penetration (I think) and so having more armor is good because let say a Panzerfaust hits the the side that doesn’t have any extra armor it will just go right through but if you add extra tracks or even more steel (as an separate but welled plate) it will go into that and the Sherman Jumbo has a higher chance of survival

Actually, in a close range combat situations. The Jumbo’s does have an advantage here unless if they’re on head to head combat. German Tank Commanders who commanded Heavy Tanks such as the Tiger-I and the King Tigers preferred to engage Allied Tanks from longer ranges, attacking Allied Tanks from 800, 500 and 100 Yards would be considered suicide due to it’s Mobility and Better Situational awareness because of Shermans having better Periscopes being traversable and does have well-placed Vision Blocks on their Cupolas.
But real Tank combat is all about who shoots first, the first shot is enough to scare away any WW2 Medium and Heavy Tanks that leads the Tanker how exposed they were to enemy fire.

It really depends on the circumstances. A Jumbo at the side of a tiger II could easily handle it, but it most likely couldn’t penetrate the front of the tiger II, except for the turret cheeks with the m1 76mm. But a jumbo shouldn’t even be engaging a tiger II, the Americans had M18s and M36s for that.

The extra armor was mainly a morale thing, even when the thing was more heavily armored than a heavy. Also one of the pictures detailed the front of a jumbo defeating a 88mm L/56 3 times before a lucky round went through an optic port..

to be fair they probably did not want to die as well as the panzer 4 could still penetrate its front thru the mg port and the long 88 could pen the front without going thru the mg port

no, but it WOULD probably make for a makeshift infantry tank, in a way… The only 105mm armed Shermans were the M4(105) and M4A3(105) Shemans.
One thing gets me though: How sucessful would it be IF a 76mm Sherman turret/T23E3 turret were to be mated with a 17-pdr? Clearly there’s gonna be some modifying to the turret, but it seems reasonable that it would be mated somehow?

In my mind that is the perfect Sherman, hull and turret of the M4A3E2 jumbo, HVSS suspension, and a 17-pdr gun, it would instill fear into the german army.

You people must just gloss right over and conveniently ignore the part where it says how “we tested it and the M4 Medium chassis CAN carry 80,000lbs, but not for normal service”. They slapped twice as much armor on a chassis than it was designed for. It was able to carry it around, but it would have made for a tank that broke down even more than Tigers. The biggest reason Germany managed to use Tigers to such good effect is that they were fighting on the defensive the majority of the time, and didn’t need to drive long distances (when they did they invariably left large numbers of destroyed Tigers behind when they broke down). Trying to drive across Europe with a bunch of M4s carrying twice the weight of armor they were designed for, AND a gun twice as heavy as intended (mostly in the nose) is a recipe for trouble. They didn’t do it because it was a bad idea, as bad as the Tiger II was. Why do you think they only built 250 of them? They were useful for a few very limited purposes, but that’s about it. And they needed constant repair to keep on the roads; the Allies were driving long distances at high speed, trying to maintain momentum. They didn’t need to be lugging a bunch of mechanical nightmares along with them.

Germans did the other way around, testing and adding weight afterwards 😀

It would make a great tank killer, but a lousy allround tank. The point of a Jumbo was having extra armour on a 75 mm gun tank because most targets were guns, infantry and “softer” AFV’s, like StuGs and Panzer IVs.

The Jumbo was impenetrable from the front by the Tiger I, save for the mg port. Even IS-2’s 122mm D-25-t was theoretically incapable of penning the frontal plate or turret of the M4A3E2.

There is a difference between theory and practice, and in reality no tank no matter how heavily armoured is truly ‘impenetrable’. It depends highly on the range the shot was fired from and the angle and location of where it impacts. For instance as the Article mentions an M4E2 was penetrated through the periscope port on the mantlet despite it being a rather small opening in the armour.

Exactly. A tank may be “impenetrable”…but only when hit square on the armor. The armor is full of gaps, welds, and other weak spots that won’t LIKELY be hit by any given shot….but that shot is going to hit SOMEWHERE, and that’s often directly on a vision slit, a MG ball mount, a weld, a shot trap, the join between turret and hull, the suspension. Even the armor itself varied a great deal; a piece that was given poor heat treatment won’t stand up to the theoretical strength. The Germans had big problems with alloys, finding the correct material, so it really depended on what specific tank you shot at. One Panther might laugh at a hit from an 85mm (frontally, anyway, not from the side or top), while it might punch right through another. A tank might be totally “impervious”, yet the shot will go right through small port anyway. All these kids who spend all their time playing WOT “knowing” which tanks are “invulnerable” to others, but it really has a hell of a lot more to do with luck and tactics than anything. No tank is invulnerable. I like the story about the M8 Greyhound that got on the road behind a Tiger II and knocked it out with its 37mm gun. You tell that to WOT players and they’d insist it was impossible, and quote you the states on the Tiger IIs rear armor and the 37mm gun’s penetration values. Yet the fact remains that IT ACTUALLY HAPPENED. They found a weak spot, and killed the tank. Period. The aviation equivalent is “the Golden BB”, where the guy on the ground with an SKS or Moisin-Nagant manages to take out a modern jet with a single lucky bullet. It’s not “impossible”, it’s “unlikely”. But it can, and does happen. You fly an F-22 overhead and a single guy with an AK can shoot it down, if he is lucky.

Okay, here’s a reply to a posting 2 1/2 years later. ( hah? )
The story of the M8 destroying a Tiger II maybe didn’t happen. I wandered across a website last year that believes no Tigers ( I or II ) in the area where the fight happened. It seems likely a Pz IV or a Stug was the actual victim.

I wonder what the 12.8cm would do, that would be an interesting one considering the fact at the point the M4A3E2 was issued and delivered the germans had a limited amount of them (although many in berlin) it would still be interesting what-if moment.

The Frontal Hull of 114-136.9mm of the Jumbos are impenetrable to the 88mm Anti-Tank Cannons and it was proven. The weaknesses of this Tank was on the less Armored sides and the rear, (including mines and a lucky shot through the optics).
This isn’t War Thunder or World of Tanks, this is Reality. A King Tiger will still not likely penetrate the Jumbo while that Tiger carries the same 88mm Gun. The Disantvantage of the King Tiger is not on it’s mechanical failures or unreliability, it says that the Welding on it’s Armor was worse than expected, even if it didn’t penetrated the Armor will result in a spalling effect, which sends bits of projectiles which can injure Crew members, even the rear is vulnerable to 76mm Guns with Armor Piercing rounds.

Tiger II are armed with 8.8 cm KwK 43, a 88 gun with more penetration than 88 found on Tiger I.

Our tank destroyer doctrine called for the Wolverines and M36’s, to kill the King tiger, from 2 miles away. (before the Sherman’s get too close.)

I have been extensively looking at a tank that I think at the very least is a M4 that is not on any lists and at most a M4A3E2. I would like to coloberat with someone to research this.

I did not see a number for how many M4A3E8s were converted to Jumbos. It says 250 M4A3E2s were ordered, so that doesn’t include the M4A3E8s that were modified. Do you have any data on how many were converted, and if so, could it be added to the article?
Thank you, great article!

Hello Officer,
If you mean the Field Expedient Jumbo, I sincerely doubt there is any counting of those. They were generally done in the field by the units, so records are probably really scarce.
Or did you mean something else?

These tanks were known as “Jumbo” by the 735th Tank Battalion. From the After Action Report, Page 44, Summary for November 1944,
b. The new “Jumbo” type tanks was first used during this period with very good results. One of these was hit by a bazooka and one by a 75mm AT gun. Very little damage was done by the bazooka and none of the crew were injured. The 75mm pierced the tank but it was at the point where the armor was thinnest, and it is not thought that it would have pierced the tank at any other point. None of the crew were injured. It is the opinion of this Bn that these tanks should be supplied in sufficient quantity to at least allow the placing of one platoon (5) of them with each Co.
The above text about “Jumo” not being a war time nickname seems to be incorrect.

As said: No
BUT! They did equip a testbed Sherman hull with a Pershing turret! The M4 Sherman, M26 Pershing, T32, T20 series (T23, T25, T26, etcetera…), M45, M46, M6 (T1), M10, Achilles, M18, and M36 all had the same turret ring diameter of 69″ and thus interchangeable turrets! You could put an M6 or T32 turret on an M18!

I have something to add to the above article. My uncle (James Garland Murphy-Bryan, Tx.) was aboard the Cobra King when it broke into Bastogne, Belgium on 26 Dec. 1944. He was killed in his tank on 19 March 1945 near Bad Kruesnech Germany, from my understanding he was the only man killed when his tank was hit and burned. What I would like to know was this the Cobra King he was in when he was killed. If so, would we have been able to repair the tank in time to join the Raid at Hammelburg?

In the 6th picture down in the Operational history if you look carefully at the bottom just right of the left track, I noticed a shell mark

Recently I visited the museum at Camp Ripley in MN where a m4e3e2 survives today and was wondering if anyone could help me find what company the tank was from. Some distinct features I could find are the two welded up holes in the front (one under to the right of the gun holder and the other right under the rivers hatch) serial number 3082941 (initially the number was 3082947 after restoration in 1983 ). It was shipped back to the US after WWII and was used for training up until 1959. it was used as a machine gun range during that time. It was then restored in 1983 and then a second time recently (couldn’t get a date). This m4a3e2 in particular has the 75 mm gun instead of the 76 mm.

If anyone has any information on this tank i would love to hear it, Thanks!

since the 17 pounder is only .2 mm greater in caliber than the Jumbo’s 76, the gun would fit fine, but the real problem would be the breech, which would almost certainly be incompatible with the already cramped M4A3E2 turret which had been pinched in with the thick 6″ armor. But if the breech fitted, then its very possible a british jumbo could have existed, much like the firefly shermans.

The 76mm gun could easily penetrate any german tank, there was no need for a bigger gun, even the 75mm could jam itself in the turret ring, take out a track or even penetrate the front of tigers and panthers at close range using the APCR round.
An 105mm gun would have no point and a howitzer would be way too hard to fit in.

a jumbo with 250mm frontal armor (with beefed-up suspension)+the Russian 85. how would that work? could it be modified to accommodate these mods? if it could it would instill fear in the German armor units. (this is completely theoretical)

Honestly, that’s not a bad plan. The 34/85 DID have a longer turret, to accommodate the 85mm, so some modification would be required. A large bustle, perhaps, or an entirely different design. Armour isn’t a problem, as the jumbo’s mantlet can bounce 88s as it is. side armor does leave something to be desired, but you can only add so much before you turn it into an american tiger 2! So, in short, yes that could work with some modification.

I gone to museum that had a running Jumbo tank and the caption with the specifications said about 250 were made. It also said there only 7 left.

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