The Jumbo Sherman- Why weren't all US tanks outfitted like this?

Jumbos weren't the only Shermans that got up armored. There were quite a few like the one shown below that were field modified with extra glacis armor. I'd say the one in the photo has about 2" more armor than a standard Sherman

 

I remember after the Janurary of 1945, the 4th Armored Division churned out a fairly large number of up-armored Sherman tanks. They swapped the existing Jumbo's 75 for a 76, and welded extra armor and a layer of concrete on some of the E8s recieved. Those tanks probably had as much as 160mm of armor. Definitely nothing to laugh at. As Terry noted, those tanks had no off-road mobility; they were used to be the lead vehicle of the column which is the tank most likely to be hit.

 

Was there a reason the US didn't start working on tanks with heavier armor and more powerful ammunition (Tiger, Panther, T34) when the other powers were having more success? Was is strictly due to mass production as we were able to make so many and modify them to fit certain situations? Or the speed and mobility?

 

As already noted, the Sherman with a substantial increase in armor became less mobile and in tank on tank combat increased frontal armor is not a panacea. The Panther with it's excellent frontal armor and long range gun, was still vulnerable and still routinely killed by the humble Sherman. The Shermans good mobility and excellent reliability was a strong point with the tank, just as the T-34's excellent cross country mobility was a stong point with that tank.
In the harsh reality of running a massive war like that in WWII Europe, logistical concerns often trump incremental increases in combat capability. So when we invaded Normandy, we relied primarily on the older M4 (welded hull) /M4A1(cast hull) versions of the Sherman due to logistical/supply issues. Incremental changes were continually introduced on the production line and many early production versions were re-built incorporating the new improved parts, but the basic tank was the same. Commonality in engine/fuel/spare parts, was the determining factor of which versions were used. The M4A2 went to the US Marine Corps and Allied nations (primarily the Soviet Union, tough some went to Britain) because it used a diesel engine and the US Army didn't want to have to provide a seperate fuel type. The M4A4 with the A57 Chrysler multi-bank engine went almost exclusively to the British due to lack of engine/transmission commonality with the M4/M4A1 in US service. The M4A1 (76) W, the cast hull M4A1 with the increased anti-armor capability of the 76mm gun mounted in the T-23 turret and wet ammo storage was available in large numbers pre-Normandy but was not introduced, again due to the desire not to overburden the supply chain. The E8 version of this tank (M4A1E8) incorporating the HVSS suspensions, 23" wide tracks, and T23 turret, was the version mentioned earlier that the Israeli's rebuilt as the M-51 "Isherman". The M4/M4A1 Shermans used a modified aircraft radial engine. Increased demand for these aircraft engines for aircraft led to the adoption of the Ford GAA V-8 engine as the powerplant for the tank and this became the M4A3 version. Again, both the M4A3 and M4A3(75)W and M4A3(76)W versions were available before Normandy but were not used due to supply chain issues, new engine, new engine parts, different transmissions. These tanks began to be fielded in the fall of 1944 once a sufficient supply of spare parts had been accumulated and they eventually began to replace the earlier radial engined versions. Most of the mid-late production M4A3's had the later, simplified, 47 degree slant glacis plate which was 1/2 inch thicker than the early production models.
Now that the background has been establised we get to the M4A3E2 "Jumbo". You take the M4A3 and add 1 1/2 inches of armor to the new 2.5" 47 degree slant glacis and to the hull sides givin the new armor thickness of 4" (2.5" + 1.5"=4") for the glacis and 3" for the sides (1.5" + 1.5"=3"). It had a new heavily armored, cast, differential cover, up to 5.5" from the standard, single piece, E4186 (2") or E8543 (4.25") covers. The turret was a heavily uparmored version of the 76mm T23, 6" thick on the sides! As other posters have noted, the added weight overburdened and compressed the VVSS springs, what they haven't mentioned is that this led to wheel bearing failure. The bearings were literally crushed by the added weight and lack of decreased play in the suspension. When possible the crews replaced their wheels with the later type welded or dished wheels with their larger bearings. I have read the same numbers for this version, 254 produced.
So it is a heavily armored tank that lacks the mobility and reliability to supplant the standard M4 in all but a narrow range of roles. It doesn't hit Europe until late fall 1944, because of logistical issues that have delayed the deployment of the entire M4A3 version of the tank. It is armed with the 75mm lower velocity gun, better suited for bunker/fortification busting, which is the intended role for the tank. The 76mm which has better anti-armor capabilities is not the standard weapon on the M4A3E2, but many are modified in the field with the 76mm to fill the role the operational units wish to use it for. Then you have the Ardennes campaign with the large loss of tanks that accompanied it. Large numbers of older tanks are rushed to Europe to make good the losses, to include many reworked training unit tanks. So you have the older 75mm armed, dry storage M4A3's appearing, even though the wet storage versions are preferred. The 76mm wet version of the M4A1, because it has the preferred gun and ammo storage, but less preferred radial engine. The M4A3E8 with the 76mm and wet storage with the new, wider, easier riding HVSS suspension is now arriving along with the first numbers of the M26 Pershing, then the war ends in May.
The reason the M4A3E2 did not see larger numbers and wider use, is simply it filled a narrow niche. Logistics prevented an earlier introduction of all M4A3 versions, not just the "Jumbo". When they were introduced the 76mm, wet sorage versions were preferred. When the M4A3E2 was modified for the 76mm gun, armor losses made the allies happy to get their hands on any armor available. Then new versions of the M4A3 with the 76mm, wet storage and a new, improved HVSS suspension was hitting the field and well liked by the crews. Finally, the M26 Pershing that was superior in virtually all aspects to the Sherman line was also beginning to be fielded.
The post war US Army standardized on the M4A3E8 version, so the military itself felt this was the most capable version and based upon its success against the T34/85 in post war encounters (mainly Korea) it appears to be the correct decision.

 

It is also always worth remembering that Germany was, to industrial/design intents, on a war footing from the moment Adolf gained power.
While the rest of the world played cricket etc., and generally focused on recovery from the Interwar recession, Germany was re-arming, and applying far more effort (if not necessarily thought) to the business of tanks (etc.) than most other nations.
The Allies played catch-up in certain technological fields, and played it well, but Germany hit the ground running.

 

Excuse me please if I resurrect this ancient topic, but I think Sheldrake in the topic http://www.ww2f.com/topic/18799-those-poor-old-shermans-it-took-5-to-kill-a-tiger/ had get the heart of the matter about the confrontation among the Sherman and the German tanks: the doctrine of use that is at the roots of the design of a tank itself. So I think we can understand why the Sherman was built with some (apparently wrong) features, only if we understand how the American Generals wanted use their tanks. So I will try to highlight how (in my opinion) some planning choices, are only the consequences of the fact that Americans and Germans had opposite ideas about the use of the tanks in battle.
For the Germans the tanks were the heart itself of the militar manoeuvre, having the task to break through the enemy lines and defeat the enemy troops, leaving to the infantry the task of to take possession of the positions. In order to do that they developed some tanks heavier of the american ones (the Sherman was about 30 ton heavys, while the Panther was about 40 tons heavy and the Tiger was even 54 tons heavy), with very thick armours, very powerful guns and a mechanical highly evolved, that allowed them to have excellent quality of tactical mobility in despite of their considerable amount; with strategic mobility I mean the movement capacity from the base to the battleground. For example on Youtube it is easy find out videos that show the infantry fighting vehicles across a bridge, while the German tanks were forced to ford the river, because the bridge wasn't enough solid for the tanks. This forced the German to choose their itinerary having high regard the solidity of bridges and the depth of the rivers; with the consequences that they could have to take a long way round in order to bypass rivers too deep and bridge not enough solid.
The Americans instead didn't had the same issue with the Sherman (but they had that issue with the heavier M-4 Jumbo and M-26), because the lightness of the Sherman made them able to pass practically everywhere. This made movement of the Allied troops extremely fast; for example the Patton's troops (2 armoured division, 4 infantry division for a total of 133.000 vehicles) spent just 120 hours to reach the sieged Bastogne and it was mid winter!
On the other hand a Sherman was completely unsuitable for a fight against a Panther or a Tiger. So why the United States didn't immediately look for a remedy for deficiency of the Sherman, maybe using a more powerful gun?
In my opinion the answer is again located in the American militar doctrine: for the American Generals the tanks didn't battle among them. In order to destroy the enemy tanks they preferred to use the aviation or the tank destroyers like the M-10, which was a Sherman with a more powerful gun, or the lighter M-18, which was a M-5 with a different gun. Such doctrine, which planned to use the Sherman only for support the infantry, showed to be very effectyve both in Italy than in France. But showed all its limits during the Battle of the Bulge, where the Allies couldn't count on the aviation for destroy the German armoured divisions. So realizing that they can't avoid the fight among tank, they decided to pun in production the M-26. That showed to be able to confront with Panther and Tigher, but it had also the same limit of strategic mobility and I think this may be the reason why the M4 were Sherman, non Jumbo: for the American Generals the Jumbo had too heavy lacks of strategic mobility.

 

The Shermans just didn't "pass everywhere", getting bogged down in mud, snow or sand was a serious issue for every experienced Sherman tank commander. At least that's what I learned from long talks with five very experienced different Sherman tank commanders and drivers. A situation like the one in Fury, where the Sherman tanks get off the agricultural road, straight into a freshly plowed and tilled field would most probably not have happened that way, the risk of getting stuck was just too big. But then again, 99,99% of what we saw in Fury would not had happened that way!

 

When I wrote, «…the lightness of the Sherman made them able to pass practically everywhere…» I was talking about bridges.

 

Oops, my bad, sorry for not reading properly mate!

 

American doctrine certainly impacted the design of the Sherman but it was more than just the tank destroyer doctrine. Armor was still suppose to penetrate the opposing line and "run wild" in their rear areas. Other players had a say in the development of American tanks though. For instance the Engineering school pretty much forced the Sherman to be limited to its design width so that they wouldn't have to buy a whole new set of bridges. Likewise it was pretty clear that the Sherman was going to have to be shipped overseas to fight. That meant if it's weight exceeded the design weight by much it would become considerably more difficult to ship. For instance it was right at the limit of the class of cranes mounted on most cargo ships that had cranes and the same class was the most common in ports I beleive.

I would disagree with this. Certainly I wouldn't want to take on a Tiger one on one with a Sherman in a meeting engagement or worse while on the offensive. However Shermans performed well vs both when used in numbers and they had the numbers and a significant RAM supperiority as well. There are a number of descriptions of some of the battles in France where Shermans came out ahead when facing Panthers as well. I beleive the book When Odds Were Even discusses some of them. Others are discussed on this forum in the Sherman specific threads and probably others as well.

It really wasn't apparent until late in the first half of 44 that a more powerful gun was needed. The US field the 76mm armed Sherman pretty quickly and had a design for a 90mm armed one on the boards. The latter was put on the back burner as the Pershing was thought to be nearer production than it turned out to be.

Aviation wasn't really that good at destroying tanks although it was good at taking out their support vehicles. It has been suggested that the death of General McNair was actually an impedement in getting improved tanks in the field. He was in Europe to see just what was happening in regards to armored warfare when he was killed much of the work he did fell to his subordinates who weren't willing to rock the boat at least until things were clearer and by that time it was too late for things to reach the field.

As I mentioned above there are some very good things discussing the Sherman and it's relative pluses and minuses as well as US doctrine on this board. You might have to look back a bit to find them though.

 

Sorry, but that always seems to be the assumption, the 'Muricans just were too dumb to realize the Sherman needed a more powerful gun (or more armor, or more mobility, depending on what their particular hobby horse is).

The problem is the original design of the M4 Medium Tank had actually considered the 3-inch Gun as one of the possible armament suites. OCM 17202 of 11 September 1941 required the gun shield and turret front design was readily adaptable to mounting the 75mm M3 Gun, a 105mm howitzer, or a 3-inch gun. The development of the more "powerful gun" installation occurred in parrallel with the development and initial production of the tank itself. By 1 August 1942 the initial installaion was tried and tested...and failed. So the intent to use a more powerful gun preceeded the Medium Tank M4 entering combat for the first time. Unfortunately what appeared to be a simple engineering task proved more difficult in reality, which can be blamed mostly on the lack of design experience in the U.S. Army Ordnance Department. The end result was the more powerful gun was delayed in production until January 1944, which meant it did not get to England until April and was not issued to units in combat until July.

 

Obviously I didn't mean that. It was only a rhetorical question to introduce the following thought.

 

I know and I was exaggerating, but in most circles even those who don't entertain the idea of American idiocy somehow miss the reality of just how things worked out. It was complicated and especially complicated on the American side by simple lack of any realistic experience in design, manufacture, or combat. I should have mentioned, the actual detailed requirement for the Medium Tank M4 was 31 August 1940. The actual design wasn't completed until a year later on 11 September 1941. In the meantime all skilled manpower crashed on the Medium Tank M3 project so that something would be available, especailly for the British, by spring 1941.

In other words, the "immediate" was the enemy of the "soon enough".

 

Since Lanciere is new here I will point out that RichTO90 has litterally written the book on this and a number of other topics related to WWII.

 

Unfortunately, the tense in that phrase should read "writing the book" since I have been working on this bear on and off for six years now. And keep learning new things, so have to add stuff and rewrite other stuff constantly...I'm working on communications now, the FM radio development story. The next section should be on fire control. Then all I have to do is finish the chapter on losses and the "Great European Tank Shortage" before I finish with the "Great Tank Scandal", which Hanson Baldwin sparked in January 1945. Should only take another couple of years or so.

I also need to find a really good first person tankers account from either Sicily or the early Italian Campaign...

 

Excuse me if I don't think it's unfurtynate if you are working on another book. Good to hear that you are still learning things because if you are I'm sure we will as well.

good luck with your research.

 

Because they didn't know what they were up against. Same thing happened with the half-tracks. Or should I say too late.

 

Anyone read a decent personal account of crewing a Jumbo?
Not sure I have - maybe bits and pieces but nothing substantial or specific.
Though... my memory...

 

It would be interesting to know if Jumbo crews were "more careful" about bogging than standard M4 ones and less prone to moving off road.

 

I suspect that other shermans weighed down with sandbags and applique armopur may have had similar difficulties