4th Guards Tank Brigade in the Berlin Offensive Operation

The following vehicles were in possession of the 4th Guards Army as of April 10th, 1945 (CAMD RF 236-2673-2714).

Vehicle	Engine-hours expended in functional vehicles						Vehicles that worked past the warranty limit
	0	0-50	50-100	100-150	150-200	200-250
T-34-85	20	16	26	36	168	-	12
T-34-76	-	4	1	-	-	-
IS-122	12	-	14	-	-	-
ISU-122	-	-	-	11	-	-
SU-100	-	-	9	20	-	-
SU-85	3	1	-	-	-	-
SU-57	-	21	14	6	2	-
MK-9/10	-	1	-	-	-	-
SU-122	3	-	-	-	-	-
SU-76	3	1	-	-	-	-

Most of these vehicles are running on V-2 variants, aside from the few oddballs: SU-57 (M2 halftrack with 57 mm AT gun), MK-9/10 (late Valentine modification), and SU-76s which run on a pair of car engines. 

There are also 10 tanks and 5 SPGs in light repairs, 24 tanks and 4 SPGs in medium repairs, and 26 tanks and 14 SPGs in major repairs, with a total of 83 vehicles undergoing repairs for all reasons.

Plan of the Berlin Offensive Operation 

After this information is gathered, the Army is thrown into the Berlin Offensive Operation. Tanks outpace infantry in deep, bold offensives to encircle the enemy, but, perhaps more importantly, reach Berlin first. A panicked note from Konev read: "Zhukov's forces are within 10 km of Berlin. You must reach the city first, at any cost." 

The 4th Guards Tank Army gets no rest. After Berlin fell, they have a new objective: eliminate the enemy forces in Czechoslovakia, so another inventory is taken. As of May 6th, the beginning of the offensive, the Army has 309 total tanks remaining in fighting condition: 203 T-34-85s, 3 T-34-76es, the one Valentine, 17 IS tanks, 30 SU-57s, 20 SU-76, 6 SU-85, 19 SU-100, 2 SU-122, and 8 ISU-122. 8 vehicles were undergoing light repairs, 48 were undergoing medium repairs, and 29 undergoing major repairs. This figure is not much greater than at the beginning of the Berlin Offensive Operation (only two additional vehicles). 11 tanks have been cleared out of the major repairs category (quite a feat, as a major repair is a total replacement of all components and is estimated to take 1600 man-hours, and even that is at a factory and not in the field). The light repair category has shrunk in half, but the medium repairs category has grown by 20 units from 28 to 48. A medium repair consists of a replacement of several assemblies, so it takes in tanks that are pretty beat up. If many tanks fall into the medium repairs category, either they have taken many hits in combat or have had many components worn down, without any specific one being a limiting factor.

The fighting force of the Army has been reduced considerably during this operation, from 412 tanks to 309. Of course, these losses weren't for nothing, as the Army destroyed the following during the course of the operation (April 16th-May 3rd):

Tanks and SPGs: 285

Guns of various calibers: 589

APCs: 225

Cars: 1562

Machineguns: 869

Mortars: 339

"Six-barreled mortars" (Nebelwerfers): 19

Motorcycles: 251

Radios: 4

Airplanes: 35

Carts: 1730

Convoys with military goods: 5

Telephone-telegraph stations: 1

Motorboats: 13

Bicycles: 2000

Rifles and submachineguns: 2500

Military warehouses: 40

Soldiers and officers: 42855

In addition to the destroyed items, the Army captured the following:

Tanks and SPGs: 25

Guns of various calibers: 62

APCs: 21

Motorcycles: 236

Cars: 1877

Machineguns: 622

Rifles and submachineguns: 6604

Airplanes (functional): 227

Airplanes (nonfunctional): 265

Locomotives: 57

Train cars: 2507

Airports: 5

Aircraft engines: 362

Airplane bombs: 3000

Parachutes: 1000

AA gun shells: 124000

Mortars: 188

Bicycles: 1300

Barges: 2

Military warehouses: 319

Factories and workshops: 110

Soldiers and officers: 31350

In addition, 38620 prisoners of war, including 10000 Soviet citizens, were liberated.

Soviet Light Tank Destoyers

The Germans were very well known for using obsolete tank chassis to create tank destroyers. The Marder series, the PzJg I, and several other designs gave new lives to obsolete light tanks. The Soviets also considered such a move.

"Report of Military Engineer 1st class comrade Afonin on a potential plan for constructing SPGs.

1. Install a 57 mm ZiS-4 gun on tanks: BT-5, T-26, T-50 and the STZ-5 tractor (with lengthened base and ZiS-16 engine).
2. Install the 85 mm AA gun on tractors: A-42 and Voroshilovets.
3. Install the 76.2 mm gun model 1927/32 on the T-26 tank.
4. Install a 37 mm automatic AA gun on the T-50, T-26, BT-5, and STZ-5 tractor (with lengthened base and ZiS-16 engine).
5. Install a 25 mm automatic AA gun on the ZiS-32 and ZiS-36 vehicles, as well as the T-40 tank and STZ-5 tractor (with lengthened base and ZiS-16 engine).

Proposals:

1. A 57 mm ZiS-4 gun cannot be used on the BT-5, T-26 and STZ-5 as a tank destroyer for the following reasons:
1. Weak armour.
2. Overloading the suspension (T-26 and STZ-5).
3. Low operational range.
4. Low ammunition capacity.
2. It is agreed that an SPG made using STZ-5 components and armed with a ZiS-4 57 mm tank gun could be used as a self propelled anti-tank weapon.
3. An SPG made using T-40 components with a 57 mm anti-tank gun is feasible.
4. The 85 mm AA gun cannot be installed on the Voroshilovets tractor for the following reasons:
1. Weak suspension (when armour is added).
2. Bore axis is too high."

Well, most of these didn't pan out. However, after subtracting the second list from the first, the following vehicles are deemed feasible:

• T-50 with a 57 mm gun.
• A-42 tractor with an 85 mm gun.
• T-26 with a 76.2 mm gun.
• 25 mm or 37 mm AA autocannons on the T-50, T-26, BT, T-40, and STZ-5, as well as some trucks.

The document is dated June 9th, 1941, so I assume that a lot of these were forgotten when the Germans showed up. However, if you're into alternate history or bashing some model kits together, that should give you plenty of new ideas.

The Soviets never quite got around to making any of those T-26 based tank destroyers, but someone did. Pz.Jag.Abt. 563 converted 10 T-26es into tank destroyers in 1943. In March of 1944, they were replaced with Marders.

As you can see by looking at the gun shields, each vehicle is slightly different. This was clearly a field conversion done out of necessity rather than something done at a factory with actual schematics.

In November of 1941, a plan came out for next year's experimental SPGs. Among the many vehicles is a directive to mount a 76 mm USV or ZiS-3 gun on the T-60. The T-60 couldn't quite manage the extra load, but, next year, a solution came: the T-70. The T-70 was sturdier, and gave the ability to finally mount the ZiS-3 gun.

"Experimental prototype of the SU-76 (SU-12) SPG built by factory #38"

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"In accordance with the decision of GOKO, factory #38 designed and produced an experimental SU-12 SPG, in October-December of 1942. The SU-12 SPG consisted of a 76 mm ZiS-3 gun on a special chassis composed of T-60 and T-70 elements. The engine assembly and transmission were positioned in parallel. The prototype was tested at Gorohovets during December 6th-16th and December 29th-31st, 1942. 

The SU-12 SPG passed trials, and was recommended by the GAU KA for the Red Army.

GOKO decree #3530 from June 7th, 1943 removed this SPG from production. The 560 SPGs that were built were modernized."

...

"According to GOKO decree #3530 from June 7th, 1943, experimental prototypes of the SU-15 and SU-16 were trialled at Gorohovets in June of 1943 by a commission led by Major-General comrade Pechenikin of the tank engineering service. It is worth noting that the GBTU KA and the commission checked the transmission and motor assembly especially thoroughly, as it performed unsatisfactorily on the SU-76 (SU-12)."

"Experimental prototype of the SU-76M (SU-15) SPG built by factory #38"

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"Experimental prototype of the SU-16 (SU-38) SPG built by factory #38"

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The "hard characteristics" of the two SPGs were more or less equal. The SU-76M had a small advantage over its five-wheeled brother: its average off-road speed was 0.5 kph higher and it had 5 degrees more gun elevation. However, comparing tanks is not that easy.

"It was discovered that the SU-15 SPG is more stable than the SU-16 during movement, and has a larger fighting compartment." 

Several defects were discovered in both SPGs, but the SU-76M performed so impressively that it was accepted into production before a second prototype was built. Trials in August of 1943 confirmed that the choice was correct. 

"The SU-76M SPG did not undergo significant changes until today. In 1944, a partial modernization and industry experience raised the quality of the SU-76M to the point where these SPGs can pass trials 3000 km long.

Engineer-Major comrade Lisin's contribution to the trials and improvements cannot be glossed over. Thanks to his determination, a series of defects was resolved in experimental prototypes and pre-production run. 

Factory #38 took four months to get the SU-76M to mass production quality, which is a good figure, especially considering the difference between it and the SU-76 (SU-12). 

The SU-16 SPG was deemed inferior to the SU-15 (SU-76M). Work on this SPG ceased when the SU-76M entered mass production."

The 1944 modernization also equipped the vehicle with a DT machinegun, and ports in the sides from which it could be fired. The MG could be mounted on the rear to fire at airborne targets. 

Even though the SU-76M was already accepted for mass production, development of similar vehicles did not cease. The SU-NATI-TsKB SPG was developed in July-October of 1943, consisting of a custom built chassis using T-80 and BA-64 components and a 76 mm K-3 gun, with ballistics equivalent to the 76 mm S-54 AA gun. 

"Experimental prototype of the SU-NATI-TsKB SPG"

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The new SPG was very different from the SU-76. It had a fully closed fighting compartment in the front of the hull. The gun was much more powerful. Both gun depression and elevation were improved. It had the same mass as the SU-76, but had a weaker engine (2x54 hp), a lower top speed (35 kph), and worse horizontal gun traverse. The SPG had serious problems with ergonomics, and did not even make it to trials.

Molotov factory (GAZ) had their own horse in the light TD race. 3 horses, even: SU-74, SU-74B (SU-57B), and SU-74D. The SU-74 was similar to the SU-12: a rear gun placement (except with an F-34 instead of a ZiS-3), front ZiS-16 engine. However, the engine failed four times over 198 km of trials in 1943, and further trials were not performed. Work on the vehicle was discontinued. That same year, the factory attempted to design a light tank destroyer once more, with the SU-74B.

SU-74B, despite its similar index, was a radically different design. The fighting compartment was now in the front instead of the back. The engine and transmission were placed in the rear. The engine was the same ZiS-16, turbocharged to 104 hp. However, this engine power was not sufficient, and the TD failed trials in August-September.

"Experimental prototype of the SU-74B SPG, designed by the Molotov Automotive Factory "

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Much like the SU-76, the TD weighed 10.5 tons and had a crew of 4, with 25 mm of armour in the front and 15 on the sides. The weak engine could only provide a maximum speed of 28.8 kph. The ZiS-4 57 mm gun could traverse vertically between -5 and +14.33 degrees and horizontally in an 18 degree arc. 

A third attempt in that same year was the SU-76D. It used the same hull, and an American made GMC diesel engine, with a different transmission. The vehicle's drive wheels were in the front. The gun was once again a 76 mm F-34. It ended up being heavier than the SU-76B, at 11.8 tons. In the same August-September trials, the vehicle was deemed acceptable, under the conditions that the engine be replaced with an improved domestic ZiS-16 and mass reduced to 11 tons. However, due to the adoption of the SU-76M, and the fact that Molotov factory could not make the required improvements in time, the SU-76D was not adopted by the Red Army, and work on it ended. The document points out that Astrov's three TDs were perfectly fine designs, but the ZiS-16 car engine could not cope with running at maximum load for a long time.

"Experimental prototype of the SU-74D SPG, designed by the Molotov Automotive Factory "

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The 110 hp diesel engine allowed the TD to reach a maximum speed of 35.8 kph, even though the average speed was not much higher than that of the SU-76B (26.6 kph vs 27 kph). The gun range was similar: -5 degrees depression, 14 degrees elevation. Despite the larger weight, the SPG carried the same amount of armour. 

In September of 1943, after the adoption of the SU-76M, Molotov factory redirected their efforts to modifications of that TD. Their first modification was quite impressive: the gun was replaced with a more powerful D-5S, and the front armour increased to a whopping 82 mm. The fighting compartment was now entirely closed. The TD was named "SU-85", with no way to differentiate it from the SU-85 on the T-34 chassis. 

"Experimental prototype of the SU-85 SPG, designed by the Molotov Automotive Factory "

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With the same pair of 70 hp engines, the 14 ton TD could reach a top speed of 36.3 kph. The TD passed 1045 km and 152 rounds of trials, but was not recommended for production, as 10 hp/ton was deemed insufficient. 

In May-September of 1944, Astrov made yet another 85 mm TD: the SU-85A. This vehicle was much closer to the mass produced SU-76M, with an 85 mm gun, a TSh-15 sight, and with additional springs on the road wheels. The SU-85A was tested much more thoroughly: 1570 km and 824 rounds at Gorohovets proving grounds, then 1028 km and 234 rounds at the NIBT proving grounds in January of 1945. The verdict was that the SU-85A requires further modification to achieve higher stability after firing and more engine power to improve off-road performance. 

"Experimental prototype of the SU-85A SPG, designed by the Molotov Automotive Factory "

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The mass of the SU-85A was reduced to 12.3 tons. That, with the same two engines, allowed it to reach a speed of 39.8 kph. This time, the front armour was the same as the SU-76M, only 25 mm. 

The SU-85A's successor, the SU-85B, was ready for trials in April of 1945. The vehicle was trialled for 1000 km and 800 rounds, and passed the trials. The more powerful engines and LB-2 85 mm gun with a muzzle brake solved previously encountered problems. Crew placement in the new widened fighting compartment allowed a very high rate or fire with the 85 mm gun, up to 10 RPM. 

"Experimental prototype of the SU-85B SPG, designed by the Molotov Automotive Factory "

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The vehicle now had a GAZ-203 model 15V engine, with 160 total hp, allowing it to nearly match the top speed of the SU-76M (43.5 kph vs 45 kph), despite its 12.4 ton mass. Unfortunately, problems arose when mass producing the LB-2 gun, leading to delays past the end of the war.

The SU-76M was also modified with 57 mm guns at the Molotov factory. Two prototypes were built, one with the same fighting compartment, and one with an altered fighting compartment, and an armoured roof. After 270 rounds fired from the first prototype and 358 rounds from the second in trials during May-June of 1944, the second prototype was recommended for adoption by the Red Army. 

"Experimental prototype of the SU-57 SPG, second variant, designed by the Molotov Automotive Factory "

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The vehicle was armed with the longer ZiS-2 57 mm gun, growing in mass by 200 kg, but otherwise unchanged. However, since the primary purpose of the SU-76M was infantry support, GBTU was unsatisfied with reducing the caliber of the gun, as well as reduced accuracy when firing at moving targets and poor ventilation of the fighting compartment. Installation of a roof and a gun with higher armour penetration was deemed undesirable.

Work on light SPGs did not end here. The SU-76M proved itself to be a powerful ally of infantry. Lightened versions of the vehicle were developed for airborne operations, but I will leave that for another article.

Lend-Lease Shopping Trip

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"Report on the question of purchasing American self-propelled guns.

If possible, I think that there is reason to purchase 90 mm AA guns on the chassis of a medium tank (used as an anti-tank gun) and 155 mm guns on the chassis of a medium tank. 

Aside from that, it is necessary to purchase quad-.50 cal machine guns on trucks. Preferably not in small numbers, but up to 1000 at a time, with 10-15 ammunition loads. 

As for the fifty 57 mm guns we were offered, I think there is reason to buy them, but only if we receive no less than 500 units at a later date.

Colonel-General Fedorenko."

Obviously the 90 mm gun on a medium tank is the M36 Jackson, and the 155 mm gun on a medium tank is the M12 Gun Motor Carriage. It is interesting to note that the report is dated June 1943 (the date is cut off), and the Jackson only started production in November of that year. The Americans must have been very forthcoming with their latest tank development information. Ultimately, no M36es or M12s were sent to the USSR. 

The quad-.50 caliber machine guns on trucks ended up materializing as the M17: four .50 caliber machine guns on the M5 US halftrack. The USSR received 1000 of them in 1944. 

M17 AA halftracks on the 3rd Belorussian Front, 1944

Here is the final conclusion for what the Red Army needed for its summer 1943 campaign:

"British and Canadian tanks:

1. Increase the number of ordered MkIII Valentines with improved armament to 2000 units.
2. Cease orders of the MkVII Tetrarch.
3. Complete the current contract for 1000 MkII Matilda tanks, and cease all subsequent orders. All incoming tanks must have 76 mm guns.
4. Begin purchase of the MkIV Churchill tank according to the current protocol for heavy tank regiments.
5. Order no less than 500 Universal APCs with a 13.5mm Boys AT rifle.

American tanks:

1. Complete the current order for 1200 M3 Stuart tanks, and cease all subsequent orders.
2. Do not order the M5 light tank, due to no advantages over the M3 light tank.
3. Complete the current order for 1000 M3 Grant medium tanks. After that, explore the question of ordering at least 1000 M4 medium tanks with a diesel engine and improved armour.
4. Order at least 500 light anti-tank SU-57 SPGs"

GABTU's Answers to the Tiger

In 1943, Tigers were deployed in sufficient numbers to become a nuisance to the Red Army. The Head Armour and Tank Directorate (GABTU) issued a set of requirements to increase effectiveness against heavily armoured tanks.

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"On the subject of combating German heavy tanks, the State Committee of Defense has established that:

1. NKV (comrade Ustinov), GAU KA (comrade Yakovlev), head of the TsAKB (comrade Grabin), director of factory #8 (comrade Fradkin), and the head engineer of factory #8 (comrade Sandler) must:
1. Increase the penetration of the 85 mm tank gun, such that it penetrates 100-110 mm of armour at 2000 meters. Present a prototype to the Kirov factory by June 15th, 1943.
2. Design and manufacture a 100 mm tank gun with a two piece shell that can penetrate 120-130 mm of armour at 2000 meters.
2. The People's Commissariat of Munitions (comrade Vannikov) and GAU KA (comrade Yakovlev) must:
1. Shortly, no later than June 1st, 1943, begin the manufacture of 57 mm HE shells.
2. Shortly, no later than June 1st, 1943, design a new AP shell for the 76 mm F-34 gun that can penetrate the side of a Tiger tank at 600 meters.
3. Shortly, no later than June 15th, 1943, develop a subcaliber round for the 76 mm F-34 gun, capable of penetrating the front of a Tiger tank at 500 meters.
3. The People's Commissariat of Tank Manufacture (comrade Zaltsmann) must:
1. Starting on May 15th, 1943, install a 57 mm tank gun (ZiS-4) on 2-3 out of 10 T-34 tanks.
2. By June 1st, 1943, build 3 prototypes of a self propelled 57 mm gun on the T-70 chassis (SU-57). The prototypes will be tested by the GAU KA in ten days from their arrival, and the result will be delivered to the GSKO.
3. By June 1943, develop a tank destroyer on the SU-152 chassis armed with a 122 mm gun model 1931, and manufacture an equal number of these new TDs as the SU-152.
4. By July 1st, 1943, develop a tank destroyer on the T-34 chassis with an 85 mm tank gun (SU-85) with a rear fighting compartment, like the SU-76."

Quite a number of requirements! Let's go through them one by one.

Factory #8 is tasked with developing new 85 and 100 mm guns. The experimental high power 85 mm gun in a penetration table from 1944 penetrates 89 mm at 2000 m. Not quite there. The existing 85 mm gun was quite effective against Tigers, so it's understandable that the high power gun was not deployed. As for the 100 mm gun, the D-10 is capable of penetrating 125 mm of armour at 2000 meters. This requirement was met.

57 mm HE shells? Against a Tiger? Well, of course not. The 57 mm HE shells were meant to make the T-34-57 (which the Soviets had since 1941, but didn't really see an opponent worthy of their high penetration guns) into a platform as versatile as the T-34-76, useful against both infantry and tanks. Since T-34-57s were built in very small numbers, it's safe to assume that even if Vannikov and Yakovlev were successful, their efforts were in vain. 

As for effectiveness against a Tiger from the side at 600 meters, the engineers only managed to ensure effectiveness at 500 meters. Many efforts to develop a viable subcaliber 76 mm shell were made, but the same penetration table only gives 92 mm of "guaranteed" penetration. I guess that number would be around 100 for "initial" penetration, so that's another checkmark. 

As I mentioned before, there was a very small numbers of T-34-57s developed, and even fewer saw combat, so the 20-30% figure was not achieved. However, since T-34-85s rolled off the assembly lines, 100% of T-34s were able to face a Tiger at long range, instead of 30%.

A SU-76 with a semi-automatic 57 mm gun was requested, and may have even been tested, but not deployed. The SU-76 was effective against infantry first, and tanks second, and a 57 mm gun would jeopardize that. The SU-57 index ended up assigned to an American Lend-Lease halftrack that mounted a 57 mm gun.

A SU-152 with an A-19 gun was never fielded, but the ISU-122 was the same thing, but on the ISU-152 chassis.

The SU-85 was, of course, mass produced, but not with a rear fighting compartment. Engineers chose the more proven design of the SU-122, with a front fighting compartment. The same design was used for the SU-100, with the aforementioned 100 mm gun.