StuG in the USSR

At the start of the Great Patriotic War, Soviet military intelligence and the GAU had a very approximate idea about the types and characteristics of German tanks. This deficiency led to an overestimation of the possibilities of German armour and the launch of the KV-3, 4, and 5 programs in March of 1941. Even information on real German tanks was sparse. Intelligence missed the increase of the front armour of PzIII and PzIV tanks to 50 mm and use of 50 mm guns. This lack of information had to be made up for in the most reliable way during the war: studying trophies. Among the vehicles that were glossed over by Soviet intelligence was the StuG assault gun.

Present from Kiev

The first use of this vehicle, envisioned by Field Marshall Manstein, was in France, in May-June of 1940. It would be incorrect so say that Soviet intelligence learned nothing about the StuG. However, it did not earn much attention, and its description was brief.

"As a rule, assault gun squadrons accompany infantry in attacks of fortified positions and strongholds in the direction of the main attack, first in motorized divisions, then later in tank and infantry divisions. The squadrons are armed with 75 mm tank guns installed on the chassis of the PzIII medium tank with a special turret and armour. The main task for these vehicles is the destruction of the enemy with direct fire."

The Soviet military had no idea about the importance and effectiveness of these low, mobile, and well armed fighting machines. Meanwhile, in June of 1941, more than 10 StuG battalions (Sturmgeschütz-Abteilung, or StuG.Abt.) assembled on the Soviet border. Among them was 197th StuG. Abt. under the command of Major Helmuth Christ.

Red Armymen posing on a captured StuG III from StuG. Abt. 197, August 1941.

This battalion was formed in October of 1940 and was armed with StuG Ausf. B vehicles. StuG. Abt. 197 had its baptism by fire alongside the 132nd Infantry Division in May of 1941 during the invasion of Yugoslavia. During the start of the invasion of the USSR, the battalion was subordinate to 

XXXXVIII Tank Corps of Army Group Center. Soon after the fighting began, it was transferred to XXXXIV Corps in Army Group South.

That same vehicle at the NIIBT Proving Grounds, early September of 1941. The damage to the suspension and the letter E on the side can be clearly seen.

On August 15th, the battalion was located at the city of Kanev, where fierce battles for the Dnieper were fought. Soviet infantry counterattacks managed to capture at least two StuG III Ausf. B from StuG. Abt. 197. The vehicles from 3rd battery was captured intact and was used in a photoshoot with the soldiers who captured it. The second vehicle, #90247 with the name Prinz Eugen, was also mobile. According to StuG. Abt. 197 records, both vehicles were lost after hitting mines. After brief repairs, they were transferred to the Soviet rear.

The assertion that at least one of the vehicles went to fight with a Soviet crew is often made, but this is not true. In early September, the vehicles from 3rd battery was already at the NIIBT Proving Grounds. As for Prinz Eugen, it was transferred to the rear of the Central Front. A brief description was composed, with the trophy getting the name "medium German tank T-3 with an immobile turret". The description included external and internal characteristics of the vehicle. These characteristics were fairly close to the real ones. Despite the urgency, the specialists who studied the vehicle had time to partially take it apart and put it back together.

The second captured StuG III Ausf. B from StuG. Abt. 197.

The NIIBT Proving Grounds went in a different direction. Instead of beginning a detailed study, they made a brief composition of its characteristics. A summary of German armour was ready by September 11th, 1941. The tactical-technical characteristics in this summary were more precise, especially when it came to armour thickness. Aside from measurements, a brief trials were also staged, where the StuG reached a speed of 50 kph.

That same vehicle from the left. This StuG had the personal name "Prinz Eugen".

In NIIBT documents, the StuG was referred to as "artillery tank" or "Artsturm" for short. It's not known who invented this term, but it stuck to the StuG in Soviet documents.

Tough Nut

The StuG III was studied to compose a guidebook on German vehicles that was so desperately needed at the front. Because of this, trials were performed in an accelerated way, and some conclusions may be unfounded.

StuG III from the rear.

"The artillery assault tank is designed to act in the first echelon of tanks. The tank has no turret. It can only fire forward in a 28 degree arc by turning the gun on a mount. There are no machineguns. The lower part of the artillery tank, the suspension, the engine, the planetary turning mechanism, and the controls are taken from the PzIII. The gearbox is the same as the one on the PzII Ausf. B and only differs in its size. 

The armour of the tank can be defeated by guns of all calibers. It is possible to destroy the tank through the opening above the gun mount using a bottle of incendiary fluid or a grenade."

The conclusions regarding protection seems hasty. Of course, there were some poor decisions made regarding the vehicle, and the protection of the casemate was one of them. The gun sight opening "caught" shells, but it was changed in the Ausf. C version. The gun mount was also far from ideal as far as shell resistance went. However, the protection offered by the front armour went underappreciated by the proving grounds. The StuG III was the first mass produced German vehicle with anti-shell armour. The front armour of even the StuG III Ausf. A was 50 mm. The vehicle was reliably protected from the 37 mm gun. The PzIII and PzIV only received improved armour a year later.

Poster with vulnerable parts of the StuG, which slightly differed in reality.

It was already obvious that the 45 mm gun will have problems with German armour in late 1940. A 30 mm thick evacuation hatch from a PzIII tank bought in Germany was fired upon, penetrated, and even shattered, but not on the first try. These results showed that thicker armour would be impenetrable. Nevertheless, in September of 1941, the verdict was "vulnerable to artillery of all calibers". The same verdict was repeated in the flyer from the "Destroy German Tanks" series.

A full fledged study of the vehicle's armour was only made in September of 1942. PzIII, PzIV, Pz38(t) and the StuG were tested at the NIIBT Proving Grounds at Kubinka and their Kazan branch. The tanks were fired upon by Soviet, American, British, German, Czechoslovak, and French tank guns. Their resistance at 50, 100, 200, 400, 600, and 800 meters was measured.

Results of firing the 45 mm gun (1 and 2).

First, the vehicle was fired upon by the 45 mm mod. 1942 tank gun in the T-70 tank. It penetrated the 30 mm armour with no problems from a range of 850 meters. Firing at the front was a different story. From 100, then 50 meters, the result was the same: 20 mm dent. The shells fell apart on impact.

Hits from 2-pdr shells. The penetration was likely by chance.

The story can end here with the conclusion that Soviet armament was bad, but similar results were shown by another gun: the British 2-pdr (40 mm) in a Canadian Valentine VII tank. The sides also proved effortless. As for the front armour, it was only penetrated once, and the penetration was deemed unsatisfactory, since the shell landed into the joint between the central and lower front plates. In all other cases, the shells made 25 mm deep dents. One can only feel sorry for British tankers whose main armament was the 2-pdr gun until the fall of 1942.

Penetrations by 37 mm subcaliber rounds from the A-7 gun on the Pz38(t)

A similar result was attained by the 37 mm A-7 gun on the Czechoslovak Pz38(t) tank. It could confidently penetrate the sides, but the front was invulnerable: the shells left 40 mm deep dents. The results were different for subcaliber shells: they could penetrate at 100, 200, and 400 meters.

The 37 mm M5 gun installed in the American light M3 tank performed better. Its M51 shell easily penetrated the front of the StuG at 100 meters, and 35-50 mm deep dents were formed at 150 meters. This can primarily be explained by the larger casing size used by Gladeon Barnes in its creation, giving the gun's shells a higher velocity compared to British and Soviet analogues.

The ordinary armour piercing shell from the M5 37 mm gun confidently penetrates the front armour.

The 47 mm SA 35 gun on the Somua S35 was even more effective. It could penetrate the front of the StuG III from 400 meters, but at this range only every other shot penetrated. The German 5 cm KwK 38 L/42, the stock armament on PzIII tanks by 1942, could penetrate the front of the StuG at 800 meters.

Penetrations left by the SA 35 gun installed in the French Somua S35 tank.

The 75 mm M2 gun used in the American M3 medium tank achieved curious results. The first Lend-Lease convoys didn't bring armour piercing ammunition, so HE was used. The results were poor, not a single penetration was made. The maximum that was achieved was a 10 mm dent. In addition, a deep dent was formed in the transmission cover while firing at the upper front plate. The 76 mm F-34 achieved different results and made Swiss cheese from the StuG at all distances. The armour caved in upon impact, forming many fragments.

Results of the 75 mm M2 gun used on the American M3 medium tank.

Landmark

At the same time, the StuG III was being studied at NII-48. The composition of the armour and joints between plates were being examined and successful design decisions that could be implemented in Soviet production were extracted. 

"The hull of the German Artsturm tank:

The hull is welded. The ceiling of the fighting compartment is attached by bolts with a hidden head. Initially, the front plate was 50 mm thick, the sides were 30 mm thick, and the rear was 20 mm thick. Later, the rear 20 mm plates were replaced by 50 mm plates.

The hull is composed of rolled Chromium steel with 0.1% Vanadium. The Brinell hardness of the plates is 337-476, the diameter of the print is 2.8-3.32. The armour is malleable, has good resistance, and doesn't chip.

...

German PzIII, PzIV, and Artsturm tanks are made with Chromium steel and have good shell resistance. The composition of armour can be used to produce armour thicker than 50 mm. Curing, rolling, thermal conditioning and welding of Chromium steels mark 5140 and 5150 is already mastered by our industry and putting this armour into production will not be a problem.

A Chromium electrode containing 2.1% Chrome and 0.2% Carbon can be recommender."

Layout of the StuG's armour from NII-48's report.

It is worth mentioning that work on 45 mm subcaliber shells and a 45 mm gun with a lengthened barrel was going on before the trials of German tanks. The results of the trials only hurried both designs.

Initially, the German novelty was of no interest to Soviet designers. Later, the StuG III had a big effect on the development of medium self propelled artillery. Before, Soviet SPG designs were, as a rule, open topped tank destroyers with rotating turrets, like the U-20 project. By spring of 1942, the priorities shifted to assault guns with closed casemates, similar to the StuG III, but that is a topic for another article.

Original article by Yuri Pasholok.

German Experience in 1942

I have written many times that penetration achieved on paper is no match for penetration achieved in combat. The Germans seem to have been in agreement, issuing a document describing effective ranges from various weapons against T-34 and KV tanks on June 21st, 1942. A translated version of the captured order containing this data is stored in CAMD RF 208-2511-1049.

Type of gun	Type of shell	Range	Tank	Effect	Notes
50L/60 tank gun	PzGr. 39	600-700	T-34 (turret)	Penetration. Ammunition can explode and the tank can burn.	At long ranges, it is still possible to jam the turret and destroy the gun.
	PzGr. 40	300-400	T-34 (turret)	Penetration only.	Same as above.
	PzGr. 40	600-700	KV-2	Penetration.	The armour is about 80 mm thick. At longer ranges, the gun can be damaged.
50L/42 tank gun	PzGr. 40	Point blank	T-34	None.	It is possible to jam the turret or damage the gun.
75 mm gun (PzIV)	Hollow charge	Up to 700 m.	T-34 (turret)	Penetration.	Crew can be knocked out by the shockwave.
	Hollow charge	Up to 2000 m.	T-34	Suppressive fire.
	Hollow charge	Up to 800 m.	Type II (all parts)	Penetration.	Tank is easily ignited.
75L/43 tank gun	PzGr. 39	Up to 800 m.	T-34	Penetration of the front turret and hull.	Under favourable conditions, the side can be penetrated at 1200 meters.
	PzGr. 39	Point blank	KV-1 (side)	Penetration.
Light field howitzer	PzGr. Rot	600	T-34	Damage to the gun.	23rd TD reports that the shell can be effectively fired from up to 1000 m. at tracks. Fire from reverse slopes.
	PzGr. Rot	400	T-26	Penetration.
	PzGr. Schwarz	300	T-26	The turret is destroyed.
105 mm leFH 18	PzGr. Rot	1200	KV-2	Front armour screen penetrated.
	PzGr. Schwarz	1000	BT	Penetration
	PzGr. Schwarz	1000	T-34	Penetration of the front hull.
50 mm Pak 38	PzGr .40	300	T-34 (turret)	Penetration	23rd TD reports effectiveness. At 800-1200 meters, the angle of meeting the sloped armour is more favourable.
	PzGr. 38	300	T-34	Penetration
	PzGr. 38	300	KV-1 and KV-2	Penetration of side and rear hull.	When shooting the rear at up to 1000 meters, there is a chance to set the tank on fire.

"The casing of PzGr. 40 frequently bursts, and the shell jams.

Rules of using AT guns: Fire from all weapons at proper distances. In cases of massed tank attacks, move the guns into the open. Against the T-34 tank, artillery fire must be concentrated, even if the armour cannot be penetrated with shells."

This document doesn't really tell us anything that we didn't know. The short 50 mm gun is ineffective at fighting T-34s, even with APCR. The longer gun of the same caliber is a little better, but only then against the turret, and not the hull (explaining the short life of up-armoured T-34s). APCR doesn't do as much damage to the insides as APHE. In this case, where the 50 mm APCR can penetrate the T-34's turret, it doesn't cause detonation of the ammunition like APHE does. 

It's interesting to note the obsession with the T-34. Heavier KV tanks are also present (as well as a drizzle of light tanks), but the T-34 receives greatest attention, with more rows dedicated to its destruction, plus additional instructions to fire even if it's ineffective.

The report contains descriptions of tactics I have already posted, along with some new points. For instance, they praise Soviet artillery.

"Enemy artillery has achieved successes in control and concentration of fire. There are cases of massed artillery fire. Because of this, we are forced to loosen our formations.

Reserve positions, ranging guns, and "migrating" guns are used skilfully. Artillery positions are masterfully camouflaged."

It is also noted that the amount and effectiveness of Soviet tank units has increased. In connection with this, tactics must be revised.

"Tanks must be constantly, up to the moment of the breakthrough, be supported by artillery fire (sometimes smoke). If possible, dive bombers must also be used.
...
It is necessary for tank units to occupy favourable positions (preferably reverse slopes), wait for enemy tanks, and then fire on them. These tactics bring greater success than excessive heroism demonstrated by frontline units."

And in the end, one little tidbit that will prove to be the curse of German vehicles for a few years to come: "There are many cases of breakdowns when they need to tow vehicles of equal or greater mass."

Caliber Breakdown on the Eastern Front

More interesting data from Igumnov's thesis, percentage breakdown of damage to tanks vs the caliber responsible. From left to right: 20 mm, 37 mm, 47 mm and 50 mm L/42, 50 mm L/60, 75 mm, 88 mm, 105 mm, 128 mm, Panzerfausts, and Unknown. 

The rows are as follows: 

Before September 1942

Stalingrad Operation, fall-winter battles of 1942-1943

Central Front, Orel Operation, 1943

1st Belorussian Front, summer operation of 1944 (June-September)

1st Belorussian Front, winter operation of 1945 (January-March)

1st Ukrainian Front (January-May 1945)

4th Ukrainian Front (January-May 1945)

1st Belorussian Front, Oder-Berlin (1945)

2nd Guards Tank Army in the Berlin Operation

Up-Armoured T-34s

All that research on additional armour didn't go to waste, and factory #112 produced 46 T-34 tanks with additional 15 and 10 mm highly hardened armour screens by May of 1943. However, this modification of the tank did not see very large scale production. Why? Because this happened:

CAMD RF 38-11355-1727

"Photo #1. Overall view of the destroyed screened tank #232. The upper part of the hull has a penetration 85 by 155 mm from a 75 mm explosive-less shell. The ammo rack detonated, the front of the hull and lower glacis plate is torn off. The tank burned down."

Turns out that the new armour doesn't protect so well from high velocity 75 mm guns. Why? Well, there's this thing called overmatch, where a shell whose caliber is larger than the thickness of the armour will perform significantly better against said armour, especially if that armour is highly hardened. A screen like this will only protect from a small caliber shell, especially a tungsten one, like 50 mm APCR, which was the original purpose of this additional armour. By 1943, there weren't many PzIIIs running around, and the Germans didn't exactly have an excess of tungsten to make APCR shells for them, so the armour wasn't very useful. But hey, on the plus side, the tank looks really good for one that had its ammo rack blow up. Let's read on.

"Photo #2. Penetration in the front left armour screen of tank #321 by a 75 mm shell.

Photo #3. Penetration of the turret skirt of tank #321, 520 mm by 120 mm from a 75 mm explosive-less shell. Largest armour fragments: 250 by 110 mm and 180 by 100 mm"

Another good example of how highly hardened armour is destroyed by overmatching.

CAMD RF 38-11355-1727

"Photo #4. The upper front of tank #100 has a breach from an 88 mm armour-piercing shell. The breach is 220 mm by 240 mm in size. A 240 mm by 110 mm fragment was torn off the driver's hatch. The tank burned. The ammunition rack, main, and secondary gas tanks detonated. The front of the tank, lower front plate, and front bottom of the hull were torn off."

Another one that's in very good condition for multiple secondary explosions and a fire.

"Photo #5. Overall view of the damage done to screened tank #111 with armour piercing 88 mm and 50 mm shells"

Well that doesn't look as bad as the others. Zoom, enhance!

"Photo #6. Tank #111. Penetration in the rear left overtrack hull from an 88 mm armour piercing shell at a 30 degree angle. Breach sizes: screen: 140 by 150 mm, main armour 150 by 90 mm."

As expected, 50 mm shells don't do anything, 88 mm shells aren't stopped by 10 extra millimeters. These weren't even plain old FlaK 36es, either. The Germans went all out on this one, and brought shiny new PaK 43s. 

CAMD RF 38-11355-1727

Combat Performance of 7.5 cm and 8.8 cm Guns

I've posted tons of very technical information on the performance of various 75 and 88 mm German guns. However, all that really doesn't say much about how well these guns performed on the battlefield. Thankfully, Colonel P.S Igumnov did all the hard work for me, and all I have to do is show figures from his doctoral thesis, "Investigation of Destruction of Domestic Tanks (using the experience of the Great Patriotic War).

Here's a nifty data set, distances of penetrations from the two aforementioned calibers:

And a nicer looking version of the data, compiled by fat-yankey. 

The data is not surprising at all. The majority of 88 mm hits are at 600-800 meters, exactly the range at which a Tiger would be engaging a T-34 according to the Tigerfibel. The mythical 2 km shots represent a negligible amount of the total. The 75 mm caliber favours closer engagements, at about 400-500 meters.

Penetration

If you read the World of Tanks forums, odds are you've seen this penetration table. Overlord even talked about it on his blog. For those unfamiliar with it, let me give you a quick translation. 

The column on the left is distance to target in meters. The first row lists the guns: "45 mm tank gun model 1938 on tank T-70", "57 mm gun ZiS-4 on tank T-34", "76 mm gun F-34 on tank T-34 and ZiS-3 on SU-76", "85 mm gun D-5 on SPG SU-85 and S-53 on tank T-34-85", "85 mm gun of increased power, experimental", "100 mm gun on SPG SU-100", "122 mm gun D-25 on tank IS and SPG ISU-122", "152 mm howitzer on SPG ISU-152" (ML-20), "122 mm gun of increased power OBM-50, experimental" (BL-9), "152 mm gun of increased power OBM-53, experimental" (BL-8, BL-10), "57 mm English gun" (6 pounder), "75 mm American gun on tank M3 Lee" (M2 tank gun), "50 mm gun Model 1938 on tank PzIII", "75 mm gun Model 1940 on tank PzIV", "75 mm gun Model 1942 on tank Panther", "88 mm gun on tank Tiger", "88 mm gun on SPG Ferdinand". 

The V0 value indicates the muzzle velocity of the shell. Under each gun name, there are two columns: one for an armour plate angled at 60 degrees from horizontal and one for an armour plate angled 90 degrees from horizontal. When two values are shown in one box, the numerator is the performance of a caliber AP shell, the denominator is the performance of a subcaliber AP shell. 

CAMD RF 81-12038-303

If you've seen it before, you also have heard criticism aimed its way. "Propaganda!" some people cry. "The 8.8L/71 penetrated 203 mm at 100 meters, not 168! This document is not to be trusted!"

They are wrong about the propaganda bit, as this was a classified internal document, used by engineers to analyze the required armour and firepower for future tanks. It would be pretty foolish to falsify these numbers. Besides, a dense table of data isn't exactly the best for propaganda material.

However, the 8.8L/71 did penetrate 203 mm of armour... when the Germans tested it. German penetration testing standards were different from the Soviets'. German penetration tests were performed with specially selected shells, against armour angled at 30 degrees. If a shell could penetrate the effective armour thickness 50% of the time (several times in a row, depending on the shell caliber), that penetration is recorded as how much that shell can penetrate.

Obviously, the Soviets didn't get courtesy shipments of special testing ammo, so they used whatever was captured along with German tanks. Therefore, these tests give a better indication of how a tank would perform on the battlefield. The Soviets had two penetration standards. When only one penetration value is shown, 75% of the shell fragments end up behind the armour plate. When two penetration values are shown, the two values are for 20% penetration (possible penetration) and 80% penetration (guaranteed penetration). So, as you can see, according to this data, while the 8.8L/71 could penetrate 203 mm of armour using special shells with 50% probability, it could only penetrate 168 mm using regular shells with 75% probability.

This document is very interesting, because it brings together most common guns of WWII (regrettably, some interesting ones are missing, like the 17 pounder or the Sherman's 76 mm gun) under the same testing conditions. This makes the comparison between the various guns much easier than having to pick through various sources, and then tring to figure out all the different test conditions.

Now, time to do some comparisons! You may have read a lot about the unprecedentedly devastating power of the Tiger's gun. However, it penetrates 120 mm at most. This is definitely high for WWII, but similar performance is reached by the Soviet 57mm ZiS-4, that was mounted on some T-34s since 1941, as well as the 85mm guns from the SU-85 and T-34-85. With APCR, even the ordinary T-34's 76 mm gun surpasses the Tiger in penetration (albeit at the expense of accuracy).

The Tiger's successor, the Tiger II, reaches better results with the 8.8L/71 gun, 168 mm. However, the D-25 gun on the IS-2 (which I compared to the 88 mm guns before) achieves nearly as much penetration, and the D-10T gun on the SU-100 (also tested on the T-34-85) surpasses it.

The Panther's long 75 mm gun also has very good penetration, and is comparable to the experimental 85 mm gun. Of course, the experimental OBM-50 and OBM-53 surpass all other guns on this table with huge penetrations of 230 mm and 244 mm, respectively. This would have been enough to take out a Maus tank, if Germany had ever sent any into battle.

In conclusion, the myth of superior German tank guns is, yet again, proven false.

See more penetration values in Penetration, part 2.