Why was it called "medium" tank

Why is the Sherman always referred to as a medium tank. It was the largest tank the Allies had in action?
The M6 and TD28 monster never saw action.

 

Well, the Churchill weighed in at almost 20,000lb more than the Sherman.....

 

The allies looked at several heavy tank designs from the British TOG to the US M6 and TD28. They chose not to build any. After Dunkirk the British needed quantity rather than quality, and after 1942 the western allies were constrained by the need to start any campaign with an amphibious landing. Allied commanders were happier with three Medium tanks rather than one heavy tank.

The Churchill and the P:z VI Tiger were both envisaged for a similar role - spearheading a breakthrough. The Churchill was an infantry tank. Slow, heavily armoured with big guns (for the British) of 75mm and 2 pdr. a British Char 1 bis with some features such as the track return at hull to height reminiscent of the WW1 tanks. The Tiger was envisaged to be the tip of the breakthrough, It was rarely used in that role, but instead grew in importance as a heavily armoured anti tank gun to engage in long range duels with the red army's tanks.

After Ww2 when the western allies faced the red hordes the British revisited heavy tanks and used the Conqueror for a while and the Chieftain is closer to the Tiger than the Panther/T34 model which inspired the Leopard/M48/Centurion developments.

 

It could be said (somewhat vaguely) that 'Medium' in early C20th tank design is perhaps as much of a concept as any direct reference to relative size. A balanced machine with no one aspect of mobility/firepower/protection dominating the other. The Jack of all trades intended for the widest usefulness.

More precisely though, there's also an evolutionary legacy to the name in the US. The post-war 'medium' ancestors of the M4 were m1921/2, T1/E1, T2, Christie types, T4, M3. All developed alongside lighter and heavier cousins. So while heavies may not have been fielded at a given time, they did exist in the world of those creating the things, and that's reflected in the nomenclature.

 

I think that nails it pretty well. The US certainly had heavy designs and even some prototypes but heavies didn't really make a great deal of sense for the US.

 

Unless, of course, you consider the M4A3E2 "Jumbo" version a heavy tank.

 

No

 

Note that the Pershing was developed as a medium tank and essentially retitled as a heavy for propaganda purposes before it was eventually retitled again back to a medium. The key may be that heavies were usually (always?) specialist tanks, often with breakthroughs as their primary role. The general wisdom, especially when you look at the evolution of tanks, is that they really weren't worth it as mediums could perform that role adequately and resulted in a more flexable and reliable force.

 

I agree lwd in your definition of heavy tanks being developed for the breakthrough role. That's why the "Jumbo" qualifies.

 

Thanks everyone-good explanation.

 

While I'd agree that Jumbo was a distinct variant of M4, I still see it as very much a Medium.

I would dispute the blanket asessment of all WW2 heavies as 'breakthrough' or 'beaten ground' types too, though there's a fine distinction and it is only words. Tiger was more of an early flowering of MBT with BFG than the true super-heavy 'Breakthrough' designs like T28 & A39 Tortoise.
The Breakthrough concept was a distinct thing. It died out, whereas 'Heavies', 'Mediums' & 'Lights' lived on for rather longer.

Jumbo... maybe 'Spearhead Medium' is the phrase. Though, again, it is only words.

 

Just words they are indeed. But, if you define a heavy/breakthrough tank as one designed in a specialist role-to break through heavily defended areas, then why wouldn't the "Jumbo" qualify? Of course, by that definition, the early Mk IV panzer certainly qualified because that was the role it was originally designed for, yet lighter than the Sherman.

Of course, by some treaty definitions, certain German destroyers could have been classified as light cruisers!

 

First of all I wouldn't define heavy as solely a "breakthrough" tank. Heavies were niche or if you prefer special purpose vehicles for the most part but they were also "heavy". The mediums were designed with exploitation as well as break throug in mind. Indeed even a light tank can be a plus over no tank if you are trying to compromise a defensive line. So the Jumbo wouldn't really be a heavy as it didn't exceed the weight of the standard Sherman by all that much and I suspect it didint' exceed the weight of the Pershing which was likely still catagorized as a medium when the Jumbo's came on line. Again the US did have some tanks it considered heavies in development and looking at them you can see why the Jumbo isn't in the running. SEe:

http://en.wikipedia.org/wiki/M6_heavy_tank
http://en.wikipedia.org/wiki/T29_Heavy_Tank
http://en.wikipedia.org/wiki/T28_Super_Heavy_Tank
http://www.militaryfactory.com/armor/detail.asp?armor_id=353

 

While we had some prototypes we were experimenting with, I somehow doubt they would have gotten beyond that stage. A couple of these made the Tiger look like a medium! Whew! So, at the end of the day the "Jumbo" was the heaviest tank we had in any numbers and was designed with the heavy tank mission in mind. If it walks like a duck, quacks like a duck,...etc.

 

Breakthrough/Beaten zone machines were a very specific concept.
Envisioned to survive against intense fortifications and trade blow for blow against such with heavy armour & armament. They're sports really, genetic oddities eventually thrown in the bucket with other aborted concepts. Possibly a red herring when looking at the more normal flows of tank design & weights.

Jumbo was intended to provide a local assault boost, a tad more survivability in a pinch to help more commonly deployed machines & men.
It was a heavily modified Medium, and came with many flaws because of that modification. I would expect a tank designated truly heavy to be able to fight under it's own power for a decent period. Jumbo was barely able to achieve this. Not a fully homogenised design really.
Same Armament as other M4s, with a certain amount of increased armour.
Walks like a slightly slow Medium, quacks with the same firepower of a Medium: It's a heavier medium with a heavier turret & superstructure.
Presumably why it's official designation was 'Assault' rather than heavy.

If looking for truly heavy relatives of Sherman, the T14 isn't a bad starting place.
Not progressed with, but an interesting shift of Shermanic concepts into a heavier frame.
Thankfully, Churchill got it's act together - can't help feeling T14 would have been a serious transatlantic cluster-F at exactly the wrong time.

 

To my way of thinking it's not just the "break through" part that's important with regards to heavies (indeed other optoins are possible such as halting breakthroughs) but the fact that they were also not designed in general to exploit far beyond the immediate battle ground. The Jumbo was not a new tank by any means I'm not even sure how much "design" went into them. Weren't many of them field mods?

 

lwd: IIRC, the "jumbos" were a rush job, made in the USA as a response to a clamor for a more robust tank to help get through the hedgerows. It came too late for that but was used, I believe, getting through the Westwall. It had its own official designation (M4A3E2) so I'm pretty sure they came from the USA and weren't just some regular Shermans with Panther armor welded on.

V.P. makes a good point though that American engine design at that period in time wasn't really up to giving the power that was needed for those heavier tanks. The German 700hp Maybach engine was probably the best of the lot during the war, even though its engineers kept many units out of service by a constant stream of modifications.

 

Indeed as you say a rush job to modify a vehicle for a particular reason. So hardly a redesign much less a new design for a tank. Furthermore it is my understanding that once the Jumbo's started reaching Europe there were field mods to produce more of them locally. I'm not an expert in this area so I don't know how common this was much less what the numbers were but again from what I read it did happen.

 

In relation to LWD's comment above about the Pershing becoming a "Heavy" then a "medium" again...I've come across the same thing happening post-war to the British Centurion. It is often described as a "heavy"...but when the Conqueror came along it was relegated to being a "medium" for the short-ish service lifetime of the Conqueror....before eventually becoming a "heavy" again!

But that was of course after a tank's weight/size began to dictate its nomenclature, rather than its intended role

 

I too wouldn't dismiss the effort involved in Jumbo too easily.
A certain degree of extemporisation, indeed, but far from a field mod. Have a look at the sheer heft of the entirely new turret castings and thickness of extra plate on the transmission cover & elsewhere and imagine the effort involved there. M4a3e2 deserved it's designation as a quite distinct variant really.


Perhaps the most remarkable thing about Jumbo, was that such an effort could be made for such a limited run so late in the war. Incredible flexibility for US industry when already running at full tilt. Just sourcing the casting capacity for the turret would be an epic job almost anywhere else. (Just cast, or cast with a rolled veneer? Can't recall, but nonetheless, an epic task in itself.)




Certainly plenty of other genuinely extemporised Sherman armour packs out there though, from the rushed to the rather professionally organised. Big subject, with much rivet-countiness entailed...