Stalingrad, Pt 2

Excerpts from Killer of Giants: Tank Hunters of the Eastern Front(London: Osprey, 1999)

The Tank Destroyer Concept

As we have seen in prior chapters, the breakthrough and manoeuvre potential of large mechanised forces posed serious difficulties for both adversaries. The war had begun with the mistaken belief that the threat posed by the tank was a solved problem, that anti-tank artillery would be a rock which tank formations would break themselves upon.

Tank forces could not fight anti-tank artillery head on, especially on well-prepared ground, so bypass or flanking attacks would be required. The challenge for the defending general was simply to identify the likely axes of advance, and to fortify them appropriately. By delaying and disrupting the advance of the armored vanguard, they could be worn down and eventually engaged by infantry in a counterattack, or his own armored forces.

The theory had not borne out. Even heavily reinforced in tight ‘pakfront’ echelons, anti-tank artillery had not proven immune to a determined combined arms assault. Additionally, the difficulty of covering the avenues of attack proved to confound even the most prepared defenses. Towed anti-tank guns had to be diffused across the line of contact, and positioned after the enemy had made his intentions clear.

Whereas the anti-tank guns were diffused, the enemy’s tanks could concentrate, and once breakthrough was achieved, divisions would be opened up to flanking attacks or even encirclement. The infantry divisions that served as the backbone of both sides’ armies would be forced to reposition, losing the advantage of their well-prepared defenses.

The first response had been to further diffuse the tank-killing power of the army. Lower level commands were stiffened with anti-tank weapons, especially ones that were more easily man-portable. The Wehrmacht pressed the obscelescent PzB 39 back into service, modified to fire shape-charge rifle grenades with greater range than infantry rifles. These tank hunters would also be equipped with a wide variety of anti-tank rifles as a stop gap.

While the Germans used rifles chambered in everything from the 7.92 x 94 mm Patronen and .55in Boys to the massive 20mm Soluthurns, the Comintern settled on a single cartridge, the excellent 14.5 x 114 mm still in service today. With muzzle velocity greater than 1000 m/s, it was a fearsome weapon against tank side armor as well as light armored vehicles, especially in heavy machine gun form.

These heavier weapons were soon supplemented by man-portable recoilless rifles and rocket launchers, able to deliver larger warheads than the infantry rifle grenade. While these weapons did not have the range or knock-out power of traditional anti-tank artillery, they were more inexpensive and portable. They could give even an ordinary infantry platoon some means to resist an enemy tank, and perhaps it was this knowledge that was most helpful.

While on the open steppes they seldom had the range to successfully engage enemy tank formations, the infantry anti-tank weapon granted the psychological boon that the ordinary soldier was not totally defenseless against the enemy’s armored behemoths. Through courage and tenacity, he could strike back, especially in forests or urban areas. That knowledge perhaps more than anything prevented the kind of ‘tank shock’ so often seen in the early days of the war, when forces routed at the sight of an approaching tank, or under the thunder of its guns.

[…]

Tanks had been fighting other tanks since the start of the war. While not the ideal arrangement for either side, who hoped to be ravaging his opponents rear areas, it often proved expedient to fight armor with armor. Assault guns designed to support the infantry with direct artillery fires were soon cross-trained in anti-tank tactics and issued armor piercing munitions in addition to their high-explosive shells. These largely casemated vehicles did not have the same flexibility as turreted tanks, but had the advantage being cheaper, usually simpler to maintain, and had a lower profile well-suited to ambush tactics.

While often referred to as tank destroyers, and pressed increasingly into that role by the constraints of total war, they are at best the transitional form. The tank destroyer as a doctrinal role, necessitating dedicated mechanised units purpose built to the tank destroyer mission, first theorized in the winter of 1940/41, a parallel development initiated by both the German Supreme Command of the Army as well as the American Central Army Commission.

As a stopgap solution, Hitler approved a crash program to convert obsolete armored fighting vehicles and their production lines to the production of a variety of different tank destroyer models. The first to reach the front was built on the chassis and running gear of the Panzer II light tank, and initially given the designation Panzerjäger II (tank hunter) before by order of Hitler it was renamed Jagdpanzer II (hunting tank).

The Jagdpanzer II mounted a 7.5 cm Pak 40, similar to the newer marks of the Panzer III medium tank. To avoid overburdening the chassis and ensure the crew could operate with reasonable speed, the gun was mounted in an open-top gun-shield. The gun was provided with a decent firing arc of ten degrees to either side, as well as ten degrees of depression, a considerable boon in hull-down fighting positions.

Similar conversions were made from the Czechoslovak LT vz. 38 and ST vz. 39 tanks, though in the latter case the engineers at BMM opted to give the resulting Jagdpanzer 39 a fully enclosed casemate. In each case, while no fault could be made to the gun itself, the haphazard nature of the conversions and the complicated logistical tail-end the repurposing left the machines with a reputation for poor reliability, and the program interfered with the Front Ford’s ambitions of industrial rationalisation.

The full measure of the hunting tank concept would not be realised until the implementation of the 1942 Total War program. In the same sea change that saw the Front Ford’s rise to the meteoric heights of the Nazi war economy and mass production of the Entwicklung series of armored fighting vehicles saw the replacement of the earlier haphazard use of assault guns and non-standardized conversions with the Wehrmacht’s first effective tank destroyer, the Jagdpanther.

Built off an improved and production streamlined version of the chassis of the failed Panzer V “Panther” medium tank, the Jagdpanther mounted a new 8.8 cm Pak 43 gun. With a longer barrel measuring 71 calibres, and larger case to pack more propellant, the Jagpanther presented a mortal threat to all its contemporaries out past a thousand metres. While the gun had already been mounted on the Jagdpanzer Ferdinand, the Jagdpanther was considerably more mobile as well as reliable, and could be produced at a much lower cost in Front Ford participating factories.

The sloped armor of the frontal casemate, 80mm at 55 degrees, rendered it essentially immune to the standard Comintern 76mm gun along the frontal arc, and still protected the vehicle very well against the newer 90mm gun.

While a deadly foe against enemy tanks, the Jagdpanther still represented a major escalation in the mechanical cost of the war. While rationalization had lowered the cost increase over older weapons, it was still a 45 tonne war machine with a very expensive main armament, one that German industry struggled to produce enough barrels and shells to arm all its armored forces.

[…]

For the WFRA, the tank destroyer concept evolved entirely separately from the casemate assault gun. The realities of the mechanised expeditionary warfare conducted in support of their Soviet allies required more than laying in wait to ambush enemy armor. Instead, tank destroyers were conceived from the outset as a specialised type of tank, keeping the flexibility of the turret. Specialised tank destroyer units would be trained in tank hunting tactics to directly engage German armor.

Such a weapon system would pare away everything unnecessary from the chassis, turning it into a mobile gun system. The first American tank destroyer project, the TD-7 Sabocat, was developed from the J. Walter Christie designed LT-7 light tank. Already a highly mobile reconnaissance vehicle, the TD-7 shed armor weight on the sides of the vehicle, and replaced the enclosed turret with a larger, open-top turret. These weight and space savings allowed the light but potent 75mm medium velocity gun to be replaced by the powerful 90mm D42 cannon, matching the firepower of the T-9 medium.

With a higher revving gasoline engine and surplus horsepower, the Sabocat could manage over 50km/hr cross country, and even higher speeds on roads. Tank destroyer battalions could take advantageous fighting positions quickly, whether in ambush or counter-attack, on the open steppes of Russia.

Weapon systems are only as good as their employment, and for the independent tank destroyer regiments the WFRA selected crews from both the tank branch and the artillery branch to meld the best skills of both. Officially part of the artillery, tank destroyer crews were well drilled in direct and indirect gunnery as well as tank hunting tactics, emphasising concealment, rapid relocation, and first hit probability. Since the TD-7 was relatively low observable and quiet, even before the addition of camouflage netting or applique, obtaining a hit on enemy tanks in the first shot served as a dramatic combat multiplier.

While Sabocats had sporadic combat history beginning in the winter fighting of 1942/43, their first en masse deployment occurred during the Second Battle of Stalingrad during July 1943. In the hot summer sun, the German armored spearheads began facing delaying actions after breaking through the first defense line. These engagements showed both the strengths and limitations of the Sabocat.

While the older Panzer IIIs and their derivatives had absolutely no defense against the powerful 90mm gun, and the once fearsome Panzer IV Nashorn could be reliably penetrated well beyond a thousand metres, by Operation Zitadelle the deadly Panzer 50 Jaguar had become the backbone of the panzertruppen, especially in such a high profile operation. The AP-82 munition that made up the bulk of the 90mm’s arsenal showed their weaknesses against the Jaguar’s well sloped upper front plate.

The standard AP-82 shot proved sub-optimal at these oblique penetration angles, and due to the structural weakness created by the shell’s bursting charge, would often shatter on impact. While this deficiency was already known, by July 1943 the only available remedy was the use of the scarce HVP-89 shot, an armor piercing composite shot with a dense tungsten sub-calibre penetrating surrounded by an aluminum body. With a higher muzzle velocity and a denser penetrator, composite shot could penetrate even uparmoured Jaguar D upper front plates at 800 metres, it had its own set of drawbacks.

Due to scarcity of tungsten and competing demands for the metal to be used in tooling, it was difficult to accept the cost of firing it out of cannons. The manufacturing process was also considerably more expensive. Consequently, HVP shot had to be parcelled out sparingly, and standing orders for even the tank destroyer regiments, who had priority for special munitions, was to only load HVP after conventional AP had failed.

At Stalingrad, tanks and tank destroyers alike compensated for this weakness by prioritizing flank ambush and counterattacks. Side on, the 90mm could do catastrophic damage to a Jaguar at nearly any range. Unfortunately, on the open steppes near the village of Grachi, this placed the tankies of the 2nd Guards Tank Army in great danger. One of the largest direct tank clashes in history, it left the fields littered with thousands of burning wrecks, with both sides suffering heavy losses. By weight of numbers and tactical aerial superiority, 2nd Guards won at great cost, functionally destroying I SS Panzerkorps as a fighting unit, ending the German offensive phase of the battle.

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Excerpts from the Uchronia forum thread “The 90mm Gamble: Logistical Genius or Penny-Pinching Tragedy?”

RuleBritannia: I wanted to dig deeper into this so-called “90mm gamble” that’s been coming up in discussions about the second world war lately. To wit, this refers to the decision of the Combined Stavka in late 1941/early 1942 to consolidate anti-tank artillery of all kinds around the 90mm D42 gun, excepting only certain specialised low volume production vehicles. Simply put, if it was meant to fight tanks or perform tank duties as a major part of its mission, it got the 90mm.

As far as weapons go, the D42 was decent. In terms of armor penetration, it’s as good as the 17-pounder, and as the Yanks love to point out, the 1.2 kg charge in the HE shell is enough to ruin anyone’s day.

But the thing is, the Germans came to the fight with bigger weapons, ones the 90mm struggled against, beginning in 1942. Rather than replace the D42, they kept trying to eek more life out of a weapon that had been designed before the war, during the period when military technology was evolving the most rapidly. They were still arming their tanks mostly with the 90mm while we were replacing 17-pounder with the much more beastly 20-pounder in medium tanks, and arming heavy tanks with even larger ordnance.

RitterStahl: The D42 was practically a copy of the 8.8 cm Flak 34 anyway, they did work on long-barreled, more powerful prototypes that pulled the same trick as the 8.8 cm PaK 42. Same proven shell + larger case + longer barrel = more penetration. But for some reason those never left the Aberdeen proving grounds.

Ubermunch: It’s not a copy.

DeOppressoLiber: I mean, it kind of is. Not in the strictest sense, but the whole 90mm family was patterned off the Flak 18/34 family. The original was given the industry code R20 and went into production at Rock Island in 1936. The operational requirement for the gun and mount system was to improve on the performance they’d observed in the German 8.8cm gun, including the ability to be readily used as a direct fire anti-tank gun.

The D42 was an improved version, developed by the Detroit Arsenal to reduce the weight and bulk to allow it to be utilized on a lighter dedicated anti-tank gun mount as well as for vehicle mounting.

EmpireOfEndlessMonologues: It was there, it was available, munitions existed already in large quantities, it performed better than either the short 88 or the 17-pounder, what more could you want? The fact that it fit in vehicles as small as the Sabocat or the air-dropable Scorpion as well as medium and heavy tanks is proof enough.

It was never going to be as powerful as the long 88, but the improved AP95 shot got it close enough. It was developed after the Battle of Stalingrad because of the difficulties they were facing against Jaguars or the other large German cats.

RitterStahl: They sacrificed on post-penetration to make the shot effective against Jaguar turret face and glacis.

DeOppressoLiber: HE filler in AP shells doesn’t work like it does in computer games. Except on the largest shells, it just makes it more prone to shattering before penetration.

Actually Empire, the AP95 was already in testing during Stalingrad, though I suppose it’s fair to say it hastened the move to mass production. When developing AP95, they took the older AP77 shot, a plain armor piercing solid shot that had been deprecated in favor of AP82, and heat-treated them to make it much harder, then welded a ballistic cap to extend effective range. They then loaded them to max chamber pressure allowed in the D42 to wring out about 910 m/s muzzle velocity. This made it good for about 220mm rolled homogenous armor.

This, plus its excellent properties against sloped armor made it effective out to 800-1000 metres for any Jaguar produced before 1944. The only downside was that the AP95 could not be used on the R20 guns, whether on the AA mounts, or the ones that used converted 76mm anti-tank mounts, and they had to recall them from any mod 1941 D42s (which mean the T-9 mod 1942 had to wait for upgrade or refurbishment) due to build quality concerns.

Pound for pound, the D42 was probably the best tank gun anyone could reasonably build in WW2, and it really didn’t get qualitatively eclipsed until you had the late war designs.

The alternative would have been one of those long barrel prototypes the OP mentioned. But those had larger case volumes, so they didn’t fit well into existing vehicles, if at all, and they wouldn’t be able to use existing stocks of HE, smoke, or incendiary shells. So I’d say the 90mm D42 gamble paid off. The Germans could not produce enough of the superheavies to matter.

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Excerpts from Bratishka: The Armored Personnel Carrier in the Soviet-German War,(Brooklyn: Simon & Shuster, 1989)

The Armored Motor Carriage Type 8 “Mishka” began its project life as the LT-8 light tank project. Designed from the outset to provide a versatile chassis to fulfill a variety of roles, the Lima plant’s project ran up against the Christie Design Bureau’s acclaim, which pushed the competing LT-7 chassis into an early lead. Beyond the political headwinds, it was becoming increasingly clear that the chassis would not meet the speed or weight requirements of the project.

However, all was not lost. The use of the novel horizontal volute spring suspension (HVSS) allowed significantly more usable internal volume compared to the CATD’s preferred torsion bar suspensions. To fill other operational requirements for auxiliary armored vehicles, the design team under Josiah Kerwin* developed a relatively novel front-engine and transmission arrangement, with the Teledyne AO-14.7 air-cooled six-cylinder ‘boxer’ type engine mated to a Telechron torque converter and transmission, with two forward and one-reverse gear. With a peak output of 210 kW, it was reasonably nimble even on the 75 RON standard fuel.

The first vehicle accepted for service was designated Mortar Motor Carriage Type 8. Armed with a 107-mm FM-12 mortar, the MMC-8 offered a compelling mix of cross-country mobility and firepower for supporting the infantry. With deployable armored covers to shield the gun-crew when the mortar wasn’t in operation, and a rear hatch to allow easy crew access, the potential for infantry transport was identified immediately.

With the Lima Arsenal’s plants already at capacity with other tank and artillery orders, production of *MC-8 variants was licensed to the International Harvester Corporation, converting most of the remaining agricultural tractor production lines to war use. Despite a few hiccups, International Harvester was able to move the first completed chassis off the line at its main Chicago plant on 7 June 1942.

As a mortar carrier, the Mishka’s were well liked by WFRA and RKKA troops alike. The 107-FM-12 “Goon Gun” was respected by friends and feared by enemies, able to lob an 11.1 kg HE shell up to 4 km, and a skilled mortar team could maintain a five RPM cadence for twenty minutes.

The AMC-8s that followed replaced a series of troublesome half-track personnel carriers in the tank and mechanized divisions of the WFRA. While the scout motor carriage derived half-tracks had performed adequately in pre-war manoeuvres, they had been unable to keep pace with tanks in difficult terrain, and terrain in the Soviet Union proved exceptionally difficult. The full-tracked AMC-8 proved resilient in the muddy rasputitsa as well as the deep snows. It was also more resilient against German infantry weapons.

Armored to resist its own 14.5 x 114-mm MG-31 in the frontal arc, Mishka were largely impervious to both German heavy machine guns as well as light autocannons. Conversely, the Germans found it difficult to justify producing armored personnel carriers capable of resisting such a powerful armor piercing round, capable of piercing 40mm of RHA at 100m. As an infantry carrier, they were capable of transporting a full section of twelve troops and their kit into combat, though troopers found manoeuvring through the rear exit challenging when the top hatches were closed. In practice, the top hatches on production versions were found to provide inadequate protection except against shell splinters, and were not thick enough to protect against rifle-calibre projectiles except at high obliquity. Consequently, they were often removed in the field, and replaced with more easily removable canvas weather covering in inclement weather.

When deployed with the mechanised units, a refined version of the existing half-track tactics were soon developed. Because the vehicle was fast, capable of 70 km/h on road, and matching light tanks cross-country, the AMC-8 would also be utilized by reconnaissance units. In the main body of the battalion battle group, they also reduced the reliance on tank desant in combined arms operations, allowing tanks to react to threats more quickly while also protecting infantry from small arms fire. Against a determined enemy position, infantry would dismount at a safe distance and assault, while their troop carriers supported the attack with heavy machine gun and mortar fires. If necessary, the AMC-8 would serve as a moving barrier to cover against small arms fire to close with the enemy, though this was more typically done with tanks. *[WPA]: Works Progress Administration *[NBI]: National Bureau of Investigation