Video: IS-3 in 1945

The IS-3 entered production shortly before Germany surrendered, but how well would it have fought if VE Day was postponed by a few months? Check out my latest video to find out.

Baby IS-3

The Second World War was a catalyst for the creation of many armoured vehicles, including heavy tanks. These vehicles were quite rare at the start of the war, but this changed radically in 1941-42. The Red Army was the most heavily invested in heavy tanks. At first, Soviet heavy tanks followed the classic path of gaining more and more weight, as a result of which the KV-1 became overloaded. The need for mobility led to the KV-13 and KV-1S. The result of this new branch of development was the IS-1 (IS-85) tank, which was quickly replaced with the IS-2 (IS-122). The tank combined powerful armament with sufficient mobility and high levels of protection. Nevertheless, work on modernizing the IS-2 began in the spring of 1944.

Kirovets-1 at the NIBT Proving Grounds, December 1944.

Pike for a Heavy Tank

Soviet tank building made a long leap during the Great Patriotic War, especially when it came to heavy tanks. For various reasons, Soviet medium tanks continued to use a pre-war chassis, but heavy tanks went through a revolutionary transformation. There was also competition among heavy tank designers, at times rougher than that of their German counterparts. The result of this competition was a rapid jump in development of heavy tanks. Development split into three directions by the summer of 1944. The first was ChKZ's Object 701, the second was the Object 252 (IS-6) developed at experimental factory #100. This was a grassroots initiative. Finally, the third direction was modernization of the IS-2 tank. Interestingly enough, factory #100 was tasked with a modernization of the IS-2, but after they started working on the IS-6 the task was given to ChKZ's SKB-2 design bureau.

Results of a Great War

Germany's surrender was signed on the night between May 8th and May 9th, 1945. The core part of the Second World War, the largest war in history, was over. The German army was not the only loser in this war. German industry also lost the battle fought in factories and on drawing boards. The Soviet Union won this battle, finishing the war with the largest tank force in the world. Unlike in the summer of 1945, this was a qualitative rather than merely a quantitative advantage. More importantly, German tank building hit a dead end, while Soviet tank building evolved down a road that later proved correct. Nevertheless, there were plenty of dead ends along the way. This article tells their story.

Armoured Confusion: Victorious '45

There are many misconceptions about the use of tanks in 1945, same as any other period of the Great Patriotic War. These myths muddle the characteristics of tanks, their application, and sometimes even introduce tanks that were not there at all. The final chapter in the series dedicated to myths on Soviet armour in the Great Patriotic War is dedicated to this period.

Long Living IS

Production of the IS-2 ended in June of 1945. The IS-3 replaced it in production. The IS-3 was supposed to replace it in service as well, and many considered the IS-3 to be a temporary tank as well. However, plans and reality are often different. Like its successor, the IS-2 stuck around for decades after the end of its production, undergoing two waves of modernization, which will be covered in this article.

Evolution and Revolution

March 29th, 1945, was an important date for Soviet tank building. The IS-3 tank, the result of a deep modernization of the IS-2 launched in April of 1944, was accepted into service on that day. The IS-3 had a complex fate. The army did not initially want to mass produce it, although the decision to do so later proved correct. The IS-3 was the last Soviet tank to be accepted into service during the Great Patriotic War. It did not reach the battlefield, but it worked flawlessly on the ideological front. The appearance of IS-3 tanks at the Victory Parade in Berlin was a true shock for the Western Allies, and this tank remained the gold standard for a modern fighting vehicle for seven years.

One Piece, IS-3 Edition

 "November 28th, 1945

To the Chief of the Main Artillery Directorate of the Red Army, comrade N.D. Yakovlev

People's Commissar of Armament comrade D.F. Ustinov

People's Commissar of Ammunition comrade B.L. Vannikov

Commander of Armoured and Motorized Forces comrade Ya.N. Fedorenko

RE: GAU letter #945369s dated November 22nd, 1945

I report that the Kirov factory produced an IS SPG equipped with an ammunition rack for single piece ammunition. This SPG will be sent to the GBTU proving grounds at Kubinka shortly.

At the same time, work was also conducted to place single piece ammunition in the IS-3 tank. It was not possible to achieve any kind of satisfactory results in this to date.

Only the SPG with ammunition racks for single piece rounds will be sent to trials.

People's Commissar of Transport Machinebuilding, V. Malyshev" 

Via Yuri Pasholok

IS-3 Production

 "To the Deputy Commander of Armoured and Mechanized Forces of the Red Army, Colonel General of the Tank Forces, comrade Korobkov

I report that:

In accordance with order of Deputy Commander of the Armoured and Mechanized Forces and the NKTP #113/023 issued on March 12th, 1945, trials of the experimental IS-3 tank produced by the Kirov factory are completed.

I present the commission's report.

Due to the fact that the IS-3 was accepted into service before the trials ended, the main design and production drawbacks discovered during the trials were reflected in minutes #1 dated March 27th and minutes #2 dated March 30th.

Drawbacks discovered during further trials and those contained in the commission's report are largely operational drawbacks.

Presently the issue that stands before the NKTP is accepting list #3 of proposals in correcting the aforementioned drawbacks.

Deputy Chief of the GBTU, Lieutenant General of the Tank Engineering Service, Lebedev

Chief of the GBTU TU, Engineer-Colonel Blagonrarov

April 27th, 1945"

CAMD RF F.38. Op.11355 D.2986 L.176

Object 704

"To GBTU TU chief, Engineer-Colonel comrade Blagonravov

I report that the Kirov factory design bureau is completing the development of an SPG on the chassis of the Kirovets-1 tank.

The hull is characterized by the following:

• Lower front plate: 120 mm at 55 degrees
• Cheek plates: 120 mm at 50 degrees
• Upper side plates: 90 mm at 45 degrees
• Upper rear plate: 60 mm at 40 degrees
• Lower side plates: 75  mm at 60 degrees
• Vertical side plates: 90 mm
• Floor and roof: 20 mm

Small Modernization of a Large Tank

Many tanks received significant upgrades after they first saw battle. Practice often trumps theory, especially during WWII where military vehicles quickly became obsolete. The IS-2 heavy tank was no exception. It was built with enough armour to protect it from the German Tiger tank, but it turned out that there were more dangerous opponents on the battlefield. As a result, a modernized IS-2 tank entered production in Chelyabinsk in late summer of 1944. It is sometimes called IS-2M or IS-2 model 1944, but neither designation was used in reality.

Object 704 Drama

"Report on the development of the 152 mm ML-20SM SPG

1. The Journal of the Artillery Committee #0254 1943 indicates that, as a result of trials and review of blueprints of the 152 mm model 1937/43 SPG, work should be done to improve the following areas:
1. Gun/breech: get rid of the muzzle brake, introduce a sliding quarter or semi automatic breech.
2. Cradle and recoil elements: simplify the recoil brake, transition to constant resistance to recoil and constant recoil length.
3. Turning mechanism: improve the design to reduce drifting of the aim and reduce effort of turning the aiming flywheel.
4. Frame, loading tray, recoil guard: review the design in order to standardize the parts and reduce their number.
2. By January of 1944, OKB-172 performed a modernization of the ML-20S, which consisted of the following:
1. Removal of the muzzle brake.
2. Introduction of a simpler recoil brake with a constant resistance and constant recoil length.
3. Shorter cradle and recoil elements.
3. Factory #172 began to work on producing a prototype of the ML-20SM. OKB-172 was told that it was expected by February 10th, 1944.
   In practice, work on the experimental prototype lasted until September of 1944.
4. After multiple requests made by the GAU to the NKTP to install the ML-20SM into a mass production ISU-152 SPG at the Kirov factory, this order was only given on October 2nd, 1944.
5. The experimental ML-20SM gun was delivered to the Kirov factory in the first half of October of 1944. As it was established later (December 12th, 1944), the gun was incomplete (lacked a turning mechanism, lacked a prepared location to install it, factory #172 did not respect the established connection between the gun and mantlet)
6. The GAU raised the issue of completing the ML-20SM to factory #172. Factory #172 representatives arrived at the Kirov factory to perform the work there in mid-February of 1945.
7. Factory #172 communicated the following to the GAU in early May of 1945:
1. The ML-20SM is being installed at the Kirov factory not in the mass production ISU-152, but in the experimental "Kirovets-2". Because of this, it is necessary to shorten the cradle and recoil elements. An agreement was reached to make changes to mass production samples, and for now the experimental ML-20SM was installed with a special mantlet (to compensate for the longer recoil elements) and presented to proving grounds trials in this manner.
8. The GAU informed comrades Ustinov, Malyshev, and Fedorenko by letter that it will only accept a fully completed ML-20SM for trials, with all changes required to install it in the new SPG. At the same time, the question of how future-proof the Kirovets-2 is was raised (May 16th, 1945).
9. The GBTU and NKTP replied that they were in agreement with the GAU, and urged the NKV to complete modifications of the ML-20SM, after which it would be sent to trials.
   The NKV insisted that the trials are to be carried out at the GAU main proving grounds without changes to the gun, claiming that it is necessary to discover additional requirements for its improvement.
10. The GAU replied that, if the trials are considered factory trials, the GAU has no issue with trials aimed at determining requirements being carried out at the GAU main proving grounds, and will aid the NKV with necessary service and supplies.
11. The NKV presented a program of trials at the start of August, and the GAU main proving grounds were ready for the trials in mid-August.
12. Factory trials of the ML-20SM at the Main proving grounds began on September 24th, 1945, and concluded on November 13th, 1945. The start and end of the trials were delayed due to a lack of NKV representatives. The GAU informed the NKV that they must be sent urgently on two occasions (September 9th and October 15th). 
13. The report on factory trials arrived at the GAU on December 6th, 1945. The main goal of the trials was to:
    Determine the quality of the weapon.
    Determine the robustness of the system as a whole and its individual components.
14. In total, 65 rounds with normal charge and 244 with increased charge were fired. Overall, including the rounds fired before arriving at the proving grounds, the gun made 576 shots, 440 of them with increased charge.
15. The SPG will be sent to the NIBT proving grounds for GBTU trials on December 21st-25th.
16. The People's Commissariat of Armament gave the order to factory #172 to produce a new MK-20SM including the required improvements described as a result of trials at the GAU proving grounds and NIBT proving grounds.

Senior Engineer of the 2nd Department of the Artillery Committee, Engineer-Major Gorbachev

December 19th, 1945"

CAMD RF 81-12038-588 pp.90-92

Beast vs Beast Killer

If you read this blog, you're probably already familiar with tests performed with 152 mm guns against King Tiger tanks. Fans of the King Tiger needn't worry about unfairness, since the ISU-152 was in turn tested against a Pak 43. A new welded hull, rather than cast, was adopted by UZTM, which already had experience with using this type of hull on IS-2 tanks. The results were quite impressive.

Modernization on Paper

Technical progress moves in giant leaps during large wars. This rule applied to nearly all types of weapons and armament during WWII, including tanks. Every year of war raised the bar of requirements, and even the newest fighting machines quickly became outdated.

The heavy IS-1 tank was created as a response to the Tiger, but was obsolete by the time it entered production. The IS-2 that came to replace it had a much more powerful gun, but it too would need to be replaced soon. Today let us remember the tanks that were supposed to replace the IS-2 in 1944. Not a single one was ever built in metal, but work on these projects resulted in the creation of the IS-2 with straight upper front hull armour and the IS-3.

Sweden's Autoloaders

Sweden's tank industry was in crisis in the second half of the 1940s. On one hand, the middle of this decade was a time when Swedish self propelled artillery thrived. That is when the Swedish army finally received assault guns, tank destroyers, and SPAAGs. However, the tank program lagged behind. Sweden's luck ran out with the Strv m/42. Pricken, LS 46, Leo, all of these projects remained on paper. Attempts to build a new tank weighing between 25 and 30 tons encountered various problems. A way out of this dead end appeared in the early 1950s, which led to two interesting heavy tank projects: the EMIL and the KRV.

Soviet Heavy Tank Characteristics

The following table compares the prospective post-war heavy tanks of the USSR (the T-34 is included for completeness' sake, but they seem to have merged the T-34 and T-34-85 into one tank). The table was approved fairly quickly after the war, since the IS-3 and IS-7 already have its index, but the IS-7 still has characteristics of the Object 257 rather than a later model, and the IS-4 is still referred to as Object 701.

IS-3 in Combat

Continued from part 1.

Trial by Combat

The first time IS-3 tanks took part in any fighting was in Hungary, in 1958. A Soviet military force was maintained there to keep communications with forces stationed in Austria. In 1955, the troops in Austria were withdrawn, and in May of that same year Hungary joined the Warsaw Pact. The Soviet troops remained, now as allies, under the name "Special Corps". It included the 2nd and 17th Guards Mechanized Divisions, 195th Fighter and 172nd Bomber Air Divisions, and auxiliary units. There were no Soviet forces within the capital, Budapest.

In 1954, the authorized strength of a division included three mechanized regiments, a tank regiment, and a heavy SPG regiment. Such a division contained 46 heavy tanks. In the mid 1950s, the most numerous heavy tanks in the Soviet Army were IS-2s and IS-3.

On October 23rd, 1956, a 200,000 strong protest occurred in Budapest, initially peacefully. The Hungarians demanded the replacement of unpopular leadership who were promoting social and economic policies pushed by Moscow.

IS-3: The Tank with a Piked Nose

The order to produce a new tank under the index IS-3 was received by Chelyabinsk factory management on December 16th, 1944. By January 25th, 1945, eight of the ten planned tanks had to be built. It took a fairly long time to build and "tune" the tanks, and they arrived in the army only by the time that the Second World War was at an end.

Goals Set by War

Spun once, the flywheel of Soviet design bureaus built up an unseen inertia by the time the war was coming to an end. Designers in Siberia, the Urals, and on the Volga overtook their colleagues in allied and enemy countries. While the first IS-2 tanks were just driving out of the Kirov Factory in Chelyabinsk (ChKZ), the design bureaus of ChKZ and factory #100 already received order #5583 from the State Committee of Defense on April 8th, 1944: design a new heavy tank. An analysis of tanks from early 1944 showed that Tigers could penetrate the cast front plate of early IS-2s from 1000-1200 meters and the Panthers could do it from 900-1000 meters. It was necessary to increase the protection of the IS-2 so that the front of the hull and turret as well as the side of the turret and the turret platform were impenetrable to German shells.

The ChKZ design bureau, headed by N.K. Dukhov and M.F. Balzhi, began its work. Their competitors from factory #100, headed by G.N. Moskvin and V.I. Tarotko also did not sit still.

IS-3 Green Light

"Conclusions

1. The IS-3 tank presented by Kirov Factory passed the 500 km long proving grounds trials. It did not pass the 1000 km warranty trial due to the fan breaking at 810 km.
2. The performance characteristics and reliability of mechanisms and assemblies of the IS-3 tank is equivalent to that of the mass production IS-122 tank.
3. The ballistics trials of the IS-3 hull demonstrate its obvious advantages over the hull of the IS-122 tank.
4. The modernized IS-3 tank is recommended for service under the condition that the defects in this report be resolved.

Deputy Chief, Scientific and Experimental Department of the NIBT Proving Grounds, Engineer-Colonel Sych

Chief of of the Tank and SPG Testing Department, Engineer-Lieutenant-Colonel Ivanov

Deputy Chief of of the Tank and SPG Testing Department, Guards Engineer-Major Bylinyak

Senior Assistant of the Chief of of the Tank and SPG Testing Department, Engineer-Lieutenant-Colonel Pankin

Senior Assistant of the Chief of the Armour, Armament, and Optics Testing Department, Grachev."

RGASPI 644-2-464

IS-2 vs. IS-3

"Comparative table of tactical-technical characteristics of heavy IS-2 and IS-3 tanks

	IS-2	IS-3
Combat weight (tons)	45.5-46.0	46.0-46.5
Length, hull (mm)	6770	6850
Full height (mm)	2730	2450
Full width (mm)	3070	3170
Clearance (mm)	470	465
Bore axis (mm)	1950	1800
Ground pressure on solid ground, kg/cm2	0.81	0.82
Armour protection, thickness and slope in mm/degrees
Upper front plate	90/60	120/55
Lower front plate	90/30	110/55
Side, vertical	90/0	90/0
Side, sloped	-	90/60
Rear	60/41-49	60/41-49
Turret front	100/0	240/0
Sides	100/20	115/45
Roof	30	20-30
Floor	20	16-20
Turret ring diameter	1800	1840
Armament
122 mm D-25 gun	1	1
DT machinegun	2	1
DShK AA machinegun	1	1
Gun ammunition	28 rounds	28 rounds
Engine
Diesel	1	1
Maximum power at 2000 RPM (hp)	600	600
Normal power (hp)	520	520
Range without refueling (km)	120-150	140-150
Transmission and chassis
Friction clutch	Multi-disk, dry
Gearbox	8 gear
Turning mechanism	Planetary, two step with friction stopper
Brake	Floating band type
Final drives	Planetary gear
Suspension	Torsion bar
Road wheels per side	6
Aiming and observation devices
Periscopic tank sight	T-Sh-14
Collimating sight	KV-T
MK-IV observation devices
Commander	1	1
Driver	2	1
Loader	1	1
Gunner	-	1

"

RGASPI 644-2-464