German WWII Assault Guns vs Tank Destroyers

[Kitsune]

Something I do not understand is why the Germans built both Assault Guns and Tank Destroyers using the same chassis and the same guns. Often Assault Guns, especially the StuG III operated as tank destroyers.

Just seems like something could have been done to simplify logistics

[Purple]

It all traces its roots back to the prewar division of labor into infantry and cruiser tanks which in turn has to do with the way guns and shells worked back in the day and the conflicting requirements of AT work and infantry support.

Firstly, not all guns are equal. A high velocity gun that is going to be good for killing tanks produces a lot more recoil than a low velocity gun of the same caliber. This puts a more or less hard limit on how big a gun you can mount on your vehicle. This is why most tanks of the era that had HV guns tended to be on the "just strong enough" side. And why for example the Panzer III could take the KwK 37 75mm LV but not the KwK 40 75mm HV. On the other hand, infantry support demands a big and heavy HE charge. Something that you can only achieve by having a rather big caliber. Thus you have a conflict of requirements which can not be settled easily. Add to this the fact that impact fuses weren't really all that accurate. So a high velocity shell like that of an AT gun would often dig it self into the ground before exploding and thus greatly reduce its effectiveness. And what you get is a very reasonable pretext for splinting vehicles firmly into the "infantry support" and "tank hunting" categories.

Now the Germans complicated this by calling all their Stug's StuG when half of them were in fact basically tank destroyers. Especially late in the war when they were extensively used as a replacement for tanks. So you get stuff like the StuG III which is basically the only way to get a KwK 40 on a Panzer III shell. But the basic context is what it is.

[energiewende]

A greater proportion of industry was able to make assault guns than turreted tanks. In reality there was no strong trade off between the production of the two.

[Thanas]

A greater proportion of industry was able to make assault guns than turreted tanks. In reality there was no strong trade off between the production of the two.

Did you even read OP's question?

[energiewende]

A greater proportion of industry was able to make assault guns than turreted tanks. In reality there was no strong trade off between the production of the two.

Did you even read OP's question?

What's the confusion? Except the very earliest StuG IIIs where a specialist low pressure gun was in fact used, for most of the production run Nazi Germany never did make assault guns or tank destroyers as such. It made cut-down versions of its tanks that could be produced by less specialised factories, so that they could be adapted under the time pressures of the war. That's the reason why there was not specialization.

I didn't answer the second point because it doesn't make sense: further specialization would only have imposed additional logistical burden.

[The Vortex Empire]

He was asking why they used the same guns and chassises for both Tank Destroyers and Assault Guns, not why they used other tank chassis's to make them.

[Thanas]

A greater proportion of industry was able to make assault guns than turreted tanks. In reality there was no strong trade off between the production of the two.

The quesstion was not "why did they build them in favor of tanks", you idiot, it was why they produced two versions of turretless designs.

[Ziggy Stardust]

It all traces its roots back to the prewar division of labor into infantry and cruiser tanks which in turn has to do with the way guns and shells worked back in the day and the conflicting requirements of AT work and infantry support.

I don't pretend to be an expert on the subject, but I seem to vaguely recall reading somewhere that World War II a lot of armies (not just the Germans) had varieties of seemingly superfluous designs simply because everything was new and modern and hadn't yet been tested in real combat. For example, wasn't it not until later in the war that the Germans discovered some of their anti-aircraft guns actually worked better as anti-tank units than anything else?

[Thanas]

No, the 88 was designed to be dual purpose from the start, otherwise it would not have had built-in depression hydraulics.

[Kitsune]

I don't pretend to be an expert on the subject, but I seem to vaguely recall reading somewhere that World War II a lot of armies (not just the Germans) had varieties of seemingly superfluous designs simply because everything was new and modern and hadn't yet been tested in real combat. For example, wasn't it not until later in the war that the Germans discovered some of their anti-aircraft guns actually worked better as anti-tank units than anything else?

A good example is the StuG IV and Jagdpanzer IV
Both are based on the Panzer IV chassis
Both the StuG IV and initial Jagdpanzer IV were armed with the 7.5 cm Pak-39/L48
While the Jagdpanzer IV later replaced that with the Pak 42 L/70, the gun made the design front heavy and actually less mobile.
Both were used as tank destroyers even though the StuG IV was originally considered an Assault Gun.
Just seems like one design would have done just as well.

[Sea Skimmer]

Heavier caliber weapons with higher angles of fall were considerable more effective against enemy fortifications, anti tank guns and infantry. For every enemy armored division, oh maybe like five infantry divisions existed, making that sort of massively important. The Germans also came to deemphasize indirect fire artillery in Panzer units because direct fire was more effective shot for shot, and the supply of guns and ammunition, and transport to move the ammo they did have, was limited. Since open topped dedicated self propelled guns were not very good against tanks, while a Stug with a 105mm howitzer could still kill some tanks, the choice was fairly logical.

One might note that the US actually put a Sherman tank into production with a 105mm howitzer in an unpowerd turret. Worked great as long as you parked on a level slope.

Of course they could have had more standardization, the Germans easily could have fought the entire war with nothing but Panzer IV variants if they'd adapted the chassis with an extra road wheel, but then you might also ask why they put two different Gewehr 41 rifles into production, or didn't keep evolving the Bf 109 to have a bubble canopy or other major improvements. Lots of dumb choices were made by Nazi hacks. Lol, we are talking about people who began to kidnap thousands of Polish children as armaments workers after murdering millions of adults.

Heer internal politics independent of strictly Naziwerfer politics also came into play, as certain forms of assault gun and all self propelled artillery came under control of the artillery, and not the Panzertruppen. Even when Guderian was made head of all Panzer design and equipment he was denied (behind his back) control of all heavy artillery vehicles.

[Kitsune]

The Bf 109 is a specific contracts while the other aircraft such as the Fw 190 is another contract. I can kind of understand that as a result.

I can understand tooling of certain factories as well. It would have time to retool. The StuG III did pretty well until the end of the War along with the Jagdpanzer 38(t). Taking the time to retool would have hurt the war effort.

Similar reason the US continued producing the M4. The US likely could have done the whole war on the M4 platform as well. The M36 mounted a 90 mm in the M4 design.

[aieeegrunt]

Stugs are simpler and cheaper to build and maintain because they omit the complexity of a turret and it's rotating gear. You can always fit a bigger gun in a hull than in a turret that fits on that hull, so making Stugs allows you to keep using production facilities for tank hulls that would otherwise be obsolete and useless. The Hetzer, an excellent late war Stug with a 75mm high velocity gun was made using the chassis of a tank that could only fit a 37mm in a turret.

Stugs usually had better armor and a lower silhouette than their tank version, which was a big advantage in WWII armoured vehicle combat.

[Dass.Kapital]

Um...not to seem picky...

But I think you'll find the Hetzer was a pretty much whole new design...Just using the facilitates in Czechoslovakian that weren't blown to smithereens (I think the factories pretty much survived after the war and...um...Switzerland? Used the updated/up gunned machines well into the 70's?)

The hull was wider then the Pz38...the running gear was modified. Not sure about the engine. I know there were attempts to put a diesel inside the little beast.

But, yes, other than being cramped as all get out, with the loading mechanism some what screwed up because of the gun placement and a few other problems, the Hetzer was a nasty little piece of tank destroyer. I also seem to remember that the whole planning and development of the machine was done in a seemingly amazing short amount of time (Hence the gun not being in the best position within the hull)

The Jadg-Panther is possibly a better example as to 'simplicity' for hull production. Though...taking away said hulls from tank production seem to create different issues.

I find it interesting that the Tiger 1 hull didn't have a 'stug' variant? Other than the half dozen or so 'Sturm-Tigers' and their ridiculously huge rocket mortar...Again, probably going back to "Keep the current tank hulls for tanks...Use the older, smaller tank hulls for mounting a bigger gun.

[AniThyng]

It boggles the mind that people answer the question of "why assault guns (StuG) and tank destroyers (JagdPanzer) when StuGs got used as TDs anyway" with the answer to "why assault guns and tank destroyers rather than tanks?".

[Rekkon]

I seem to recall that the Stug IV was put into production to make up for a loss of Stug IIII capacity due to bombing. So it was just an available design that a different factory could churn out to fill the same role.

[Simon_Jester]

It boggles the mind that people answer the question of "why assault guns (StuG) and tank destroyers (JagdPanzer) when StuGs got used as TDs anyway" with the answer to "why assault guns and tank destroyers rather than tanks?".

To directly address the question, I think it's because a dedicated tank destroyer has features that an assault gun used as a tank destroyer does not, which will probably make it more effective at the stated mission. It's not just about the gun, it's about the optics and sighting, how the vehicle is laid out, whether target profile is handled well, and I suspect other issues I haven't thought of.

I mean, a lot of WWII American tank destroyers like the M10 got used as tanks on the orders of field-grade infantry officers who didn't understand that the tank destroyer column which had just driven up was NOT equivalent to a real tank unit, and had neither the training nor the protection to get into close combat with enemy defenses. Sometimes, though, the M10s managed to win anyway. This does not mean that replacing the US Army's Shermans with M10s would have been a good idea, though.

By the same token, replacing tank destroyers with assault guns might well NOT pay off.

But I think you'll find the Hetzer was a pretty much whole new design...Just using the facilitates in Czechoslovakian that weren't blown to smithereens (I think the factories pretty much survived after the war and...um...Switzerland? Used the updated/up gunned machines well into the 70's?)

The hull was wider then the Pz38...the running gear was modified. Not sure about the engine. I know there were attempts to put a diesel inside the little beast.

But, yes, other than being cramped as all get out, with the loading mechanism some what screwed up because of the gun placement and a few other problems, the Hetzer was a nasty little piece of tank destroyer. I also seem to remember that the whole planning and development of the machine was done in a seemingly amazing short amount of time (Hence the gun not being in the best position within the hull)

As I understand it, the Hetzer was a late-war improvisation, the product of Guderian going "oh shit, we need to rationalize production and while we're at it we need a way to make sixteen tons of AFV kill sixty tons of Soviet tanks."

That sort of thing can be done quite quickly, if it's driven by a cut-the-bullshit approach to design, and if you're willing to tolerate some fairly serious bugs in detail design, like the tank's hull not sitting parallel to the ground because of all the extra weight in the front end.

I find it interesting that the Tiger 1 hull didn't have a 'stug' variant? Other than the half dozen or so 'Sturm-Tigers' and their ridiculously huge rocket mortar...Again, probably going back to "Keep the current tank hulls for tanks...Use the older, smaller tank hulls for mounting a bigger gun.

Very few Tigers were actually built, and the Tiger I was quite capable of carrying a main gun that was heavy enough. There just weren't that many things on a battlefield that the Tiger I could reasonably fail to kill at its typical combat ranges. The Tiger I was a 55-ton tank, with armor and firepower to scale; the Panther at 45 tons was nearly as dangerous.

Meanwhile, the only other tank chassis in German service were in the 15-25 ton weight class: the 38(t), the Panzer III and IV chassis, and so on. Ton for ton, were readily matched or overmatched by the T-34 and Sherman- the heavier vehicle can afford to mount more protection and a heavier weapon.

To recover some kind of equal footing, the Germans had little choice but to convert their lighter tank designs into tank destroyers. However, the 45-ton and 55-ton tanks could compete reasonably well and were not simply rendered obsolete on the battlefield. Even though the Germans had plenty of incentive to simplify their production, that didn't automatically mean they would stop building the design they had in favor of fixed-gun tank destroyers or assault guns.

[Another thought; because the Germans were keeping up heavy tank production even after the Tiger I was no longer in production, they may have had to use their heavy tank factories to turn out the Tiger II. There may have been no surplus Tiger I production capacity that could be readily rerouted into building a tank destroyer]

[Sea Skimmer]

Um...not to seem picky...

But I think you'll find the Hetzer was a pretty much whole new design...Just using the facilitates in Czechoslovakian that weren't blown to smithereens (I think the factories pretty much survived after the war and...um...Switzerland? Used the updated/up gunned machines well into the 70's?)

The hull was wider then the Pz38...the running gear was modified. Not sure about the engine. I know there were attempts to put a diesel inside the little beast.

It was functionally all new, kinda just designed off the known 38's dimensions, and not all of them were produced in Czechoslovakia either. The basic requirement was a vehicle as cheap as possible to replace all existing improvised tank destroyers, and towed 75mm Pak guns, so that the anti tank battalions of all infantry divisions could be mechanized. It was never intended to equip Panzer units or replace the Stug series, which were deployed in separate battalions/brigades only attached to infantry divisions, though integral to Panzer units.

Towed 75mm guns could still kill tanks at the time, 1943, but it was basically a 1:1 trade of guns for tanks, which was not good. All the more so since even more of the guns would end up lost to artillery fire or be abandon in action because the prime movers were not armored. As it was the Germans did hope to quickly replace the Hetzer with the smaller E-series vehicles that would have solved its problems. IIRC didn't they prototype the hull for the E-10?

Interestingly the Soviets designed a similar vehicle family, though never built many.
http://henk.fox3000.com/Hetzer.htm

I find it interesting that the Tiger 1 hull didn't have a 'stug' variant? Other than the half dozen or so 'Sturm-Tigers' and their ridiculously huge rocket mortar...Again, probably going back to "Keep the current tank hulls for tanks...Use the older, smaller tank hulls for mounting a bigger gun.

The rocket mortar version was supposed to have a stubby 21cm howitzer, which would have made it very Stug like. This weapon was never fielded however, likely due to the 1942 decision to cease all work on artillery bigger then 17cm. The rocket mortar was off the shelf and made more sense for anti fortification work in certain respects, the film of it in action in Warsaw suggests accuracy was not as terrible as you might expect. Tiger 1 also did have a weapons carrier variant planned, though it used some Panther parts as well. 17cm gun, 305mm howitzer and 305mm and 21cm mortars planned IIRC. A much more modified version was supposed to help move the 24cm K4 gun as well, which was a stupid huge weapon that apparently would have moved in two pieces. Which was a vast improvement from the towed K3 which moved in five pieces, not counting its two piece assembly gantry; though you could actually put it together in about two hours.

The suspension and drive train of the Tiger 1 were really expensive to produce though, so deleting the turret wouldn't have led to the major cost reduction you got with typical casmate vehicles. That likely helped put the breaks on getting most of these variants into service.

[Sea Skimmer]

I seem to recall that the Stug IV was put into production to make up for a loss of Stug IIII capacity due to bombing. So it was just an available design that a different factory could churn out to fill the same role.

Basically the thing was Krupp didn't make the Panzer III/Stug III, it was a Daimler-Benz product. Krupp did make the Panzer IV but the original plan was to make all the casemate versions tank destroyer Jagpanzer IVs with the long 70cal gun. Indeed at one point the plan was to completely stop making the Panzer IV as a tank, they'd all have been Jagpanzer IVs. Guderian claimed to have managed to stop that (his book is self serving, I dunno if we have any other record of the claim), as then at the time, early 1943 or so, production would have been something comically low like 100 Panthers and 50 Tigers per month, and that's it.

Then bombing did indeed disrupt Stug III production and the 70cal gun was in short supply so they had Krupp start making the Stug IV on the side. Some Jagpanzer IVs had the 48cal 75mm gun as well, making for super redundant production, though as it turned out the 70cal 75mm really overloaded the front roadwheels on the chassis anyway. So much that they had to take the rubber off them as it would be ground off and cause the vehicle to throw its tracks on a regular basis.

This is a reason why I say the Germans could have gone the whole war with a lengthened Panzer IV; as such a hull was designed and could then reasonably take even the 88mm 71cal gun. The 75mm 70cal would be no problem at all, and might plausibly work in a turret, I think they made sketches of that. Though such a vehicle would still have relatively light armor and need a bigger engine.

[Simon_Jester]

Hm. One thought:

The heavier a tank gets using the WWII technical palette, the more of a bitch it is to design an engine and suspension capable of making it move. Especially to make it move like a tank, which means having the drive train and suspension taking a hellacious pounding over just about every kind of crappy terrain imaginable up to and including bomb craters, while burdened with a truly unreasonable amount of armor plate.

As Skimmer notes, if producing the chassis for a vehicle is expensive enough, making a tank destroyer out of it just doesn't pay; you're not saving enough money that way, and you don't simplify maintenance much if at all. I don't remember if the Soviets seriously tried to produce a tank destroyer on the IS chassis either, and I know the US and Britain had no such heavy tank destroyers outside the prototype phase.

[Vendetta]

I think part of the issue comes from the fact that "assault gun" and "tank destroyer" were somewhat floating definitions, whatever gun was to hand that was able to do the job was used to do that job.
The StuG was designed as a close infantry support self propelled artillery weapon which could be used to break open fortifications, but when the Germans encountered the first T-34 and KV tanks it became the answer to the question "what can we cheaply mount a gun capable of defeating these tanks on", since the existing Panzer III wasn't up to the task, at which point it was upgunned with first the 75mm L/43 and then the L/48.

But those guns could still fire HE shells so it could still be used in its original role, it just happened to also be able to engage enemy armour.

As for why there were all sorts of StuG IV and JagdPanzer IV and Elefants and whatever that's because German industry in the war had a tendency to pull in as many different directions as it could, factories built one type of tank and weren't tooled for any others, and the drive to standardise armoured vehicle production with the Entwicklung series came too late after they'd lost too much capacity to do much with the idea.

I don't remember if the Soviets seriously tried to produce a tank destroyer on the IS chassis either, and I know the US and Britain had no such heavy tank destroyers outside the prototype phase.

Err, yeah. The ISU-152 is a real thing, a casemate mounting on an IS chassis that mounts a 152mm artillery gun, 4600 built. Like the StuG it's technically an assault gun, but if that's what you had to hand and needed to shoot a tank, then it was a tank destroyer.

[Simon_Jester]

I think part of the issue comes from the fact that "assault gun" and "tank destroyer" were somewhat floating definitions, whatever gun was to hand that was able to do the job was used to do that job.
The StuG was designed as a close infantry support self propelled artillery weapon which could be used to break open fortifications, but when the Germans encountered the first T-34 and KV tanks it became the answer to the question "what can we cheaply mount a gun capable of defeating these tanks on", since the existing Panzer III wasn't up to the task, at which point it was upgunned with first the 75mm L/43 and then the L/48.

But those guns could still fire HE shells so it could still be used in its original role, it just happened to also be able to engage enemy armour.

As for why there were all sorts of StuG IV and JagdPanzer IV and Elefants and whatever that's because German industry in the war had a tendency to pull in as many different directions as it could, factories built one type of tank and weren't tooled for any others, and the drive to standardise armoured vehicle production with the Entwicklung series came too late after they'd lost too much capacity to do much with the idea.

It's actually fairly normal for factories to only be tooled for one type of tank, and for retooling to be a major investment. The US had a lot of factories that were basically purpose-built to make Shermans, the Soviets standardized on the T-34 swarm that replaced a host of prewar tank types for a reason, and so on.

Germany's problem was that once they'd started fighting the land war they literally couldn't stop producing, even for a short time- so every production line they had needed to stay in operation making something. They could set up entirely new facilities to make bigger, nastier vehicles, but they couldn't afford to shut down an existing tank factory for 6-12 months to retool it.

Everyone else was in the same situation, but at least they, unlike Germany, weren't trapped using production lines for tanks designed in 1938. That was part of the price Germany paid for doing their war mobilization in the mid- to late 1930s so they'd be ready for the war.

I don't remember if the Soviets seriously tried to produce a tank destroyer on the IS chassis either, and I know the US and Britain had no such heavy tank destroyers outside the prototype phase.

Err, yeah. The ISU-152 is a real thing, a casemate mounting on an IS chassis that mounts a 152mm artillery gun, 4600 built. Like the StuG it's technically an assault gun, but if that's what you had to hand and needed to shoot a tank, then it was a tank destroyer.

Ah-HA. See, I honestly, quite literally did not remember that. The only heavy Soviet tank destroyers I could specifically remember were weirdo prototypes.

Thanks for reminding me. Sorry.

And yes; if it destroys tanks, it's a tank destroyer. Seems fair to me.

[Sea Skimmer]

A dedicated tank destroyer version of the ISU-152 did exist for the record, with the ever so useful designation of ISU-152-2. It had a freaking 50cal 152mm gun on it, but also had some major problems such as being nearly impossible to load and the barrel overhang being so long it became difficult to turn the vehicle were any sort of clutter in the way. War ended before the more addressable technical problems were solved but they were serious about fielding it.

The Soviets were big fans overall of fielding both assault and anti tank vehicles, it was just since the SU-100 could kill the Tiger 1 and Panther at a range of about two kilometers, it took the appearance of the King Tiger to really get the ball rolling on even heavier designs like ISU-152-2. But the King Tiger appeared too late for anyone to really get far on countermeasures; the Elephant was too rare to make countering it a super priority, though does seem to have been the original spark behind the commie monster gun.

Postwar they were basically the only people other then Sweden (ignoring some short lived two gun German bouts of insanity much later) to keep up serious work on casemate vehicles too, but in the end the lack of main elevation inherent to such designs killed them all off. Instead they built the 2S1 and 2S3 with a lot more emphasis on direct fire then was found in turreted western SP turreted weapons. Though that didn't stop some US Army M109s from knocking out T-72s with direct fire in Baghdad in 2003. T-72 can't get a break.

[Zinegata]

Something I do not understand is why the Germans built both Assault Guns and Tank Destroyers using the same chassis and the same guns. Often Assault Guns, especially the StuG III operated as tank destroyers.

Just seems like something could have been done to simplify logistics

As other have noted, the line between Assault Guns (Sturmgeschütz) and Tank Destroyers (Panzerjaegers) is pretty thin to begin with.

From an organizational standpoint, one could look at the Assault guns as primarily infantry-support units, being armored and motorized versions of the infantry guns(e.g. 75mm pieces man-handled to take out fortifications); whereas the Panzerjaegers are motorized and armored versions of towed anti-tank guns. And there are seperate "Sturmgeschutz" units (usually brigade-sized), as well as Panzerjaeger units (usually battalions directly under the command of a Division, infantry or Panzer).

Note also that Germany wasn't the only nation to do these kinds of organizational splits - the US Army for instance had a "Tank" arm and a "Tank Destroyer" arm, both of which relied largely on the Sherman tank chassis.

That said, much like in the case of the US Tank / Tank Destroyer units, the division of labor between the two arms rapidly became blurred to the point of irrelevancy. By and large one could substitute an assault gun for a tank destroyer in most situations (except for highly specialized variants, like the Sturmtiger). At which point, the differences in unit designation were mostly irrelevant.

Also, production of different types continued simply because in many cases Germany couldn't (or wouldn't) shift to making fewer models. The Hetzer for instance came out simply because they still had the 38t factory working and they had to make it produce something that could take on newer Allied tanks; in an ideal world such a stopgap tank would be unnecessary and everything would be a Stug. Similarly, Guderian (and modern-day tank observers) have no idea why the Jagdpanzer IV was even built in the first place when it was failing to properly mount the 75mm L70 (which was its only redeeming feature over the Stugs), to which a lot of historians explain as "Hitler wanted it" or "His cronies wanted it".