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Artillery of the Red Army Part II

SU-122

Artillery of the Red Army
Part Two: Self-propelled Artillery


By Ian Galley

Part 1...

The Red Army started World War Two without a self-propelled artillery arm. By the end of the war self-propelled assault guns made up 40% of Soviet armour stocks. This great difference between the start and the end of the war is an indication of how effective the Red Army found self-propelled artillery to be.

History and Development

During the 1930s, many experimental self-propelled artillery vehicles were designed and constructed. None of these projects were accepted for service. One reason for this was that Soviet heavy industry was already tied up in producing the massive amount of tanks called for under Stalin’s rearmament program – nothing could be spared to create a mobile artillery force.

Another reason was that self-propelled artillery used in an indirect fire role was considered pointless, as the time required to set up and prepare the firing position and communications negated the speed at which self-propelled guns could get into position. Lighter guns were also expected to do much of their artillery preparation by direct fire, so no need was seen for an additional self-propelled artillery arm to do this job.

Lastly, Soviet tanks of the ‘30s had large calibre guns – 45mm or 76.2mm usually – so Soviet commanders felt they could act as their own mobile artillery.

SU-76M
The Early Stages of the War: Lessons Learned

The surprise German invasion in 1941 inflicted massive losses on the Red Army tank force. Soviet industry was forced to play catch-up and focused on churning out a limited number of standardised designs (T-34, KV-1, T-70). Research on new designs was put on hold while replacement tanks were churned out as fast as possible.

SU-122

By 1942 sufficient breathing space had been gained for Soviet planners to review some lessons learned from the fighting so far. One thing they noted was the effectiveness of the German Sturmgeshutz series of assault guns. It was decided that the Red Army needed it’s own self-propelled artillery pieces, and one was to be built on the hull of the T-70 light tank (the SU-76), and another on the hull of the T-34 medium tank (the SU-122).

Once in production, turretless self-propelled guns have the advantage that they are simpler and quicker to produce than tanks. 

Apart from these designs, the Red Army constructed a wartime improvisation SP gun, consisting of a M1941 57mm anti-tank gun mounted on a Komsomolets tractor, called a ZIS-30. 100 were produced and they were used around the bitter fighting for Moscow in the winter of ’41-’42. They were effective enough for an improvised design, and showed the value of a SP gun.
The First Soviet Self-propelled Guns

The two new Soviet assault guns (SU-76 and SU-122) were designed and tested during 1942, and formally accepted for production at the end of that year.

The SU-76 subsequently proved to be a flawed design and after 360 had been produced it had to be sent back to the factory for redesign. As a desperate interim measure, the 76.2mm ZIS-3 gun was mounted on captured Panzer III chassis, and designated the SU-76i.

SU-76i
SU-76M

These hybrids were successful enough, but eventually they were phased out of service due to a shortage of captured spare parts and because the true SU-76 (now called the SU-76m) was accepted back into service.

The SU-76 went on to be by far the most common Soviet self-propelled gun, with nearly 13,000 being produced. They were lightly armoured, open topped (which made them cold in winter and dangerous to be in when involved in street fighting), but they were mobile and hard-hitting. They were (more or less) affectionately called ‘Suka’ by their crews, which was derived from the ‘SU’ and meant “Bitch”. 

The medium SU-122 ultimately proved to be a less successful design and 1,148 were produced before it was replaced by the SU-85 at the end of 1943. While the HE power of the 122mm ML-30 M1938 howitzer was appreciated by the troops, the weapon had relatively poor performance against tanks, giving the SU-122 limited usefulness. It was also much more expensive to build than an SU-76. Still, the SU-122 was an important step in that it gave the Red Army much valuable experience in using self-propelled guns.
Another vehicle that provided valuable service and experience for the Red Army was the lend-lease T-48 GMC. This was a US vehicle mounting a 57mm anti-tank gun on an M3A1 half-track. The Russians called it the SU-57 and, while the gun was considered only moderately powerful, the vehicle was appreciated for its manoeuvrability, and the vehicle was used as a dedicated SP anti-tank gun. 650 were shipped to Russia and by February 1944 several SU brigades were entirely equipped with the SU-57.
SU-57
Destroyed T-34

This was the largest concentration of a single type of lend-lease equipment in a specific unit anywhere.

Things got quite scary for Red Army High Command when, on 16th September 1942, the German Panzerkampfwagen Mark VI, or “Tiger” heavy tank appeared on the Eastern Front for the first time. This was a 56-ton behemoth of a tank, with a long-ranged and very powerful 88mm gun. Tests on a captured example in January 1943 showed that the 76.2mm field gun was useless against the Tiger. However, the 85mm anti-aircraft gun was of some use, and the 122mm A-19 and 152mm ML-20 corps artillery pieces were very effective.

Soviet command took these lessons to heart and ordered the development of a new range of medium and heavy self-propelled guns mounting powerful, large-calibre cannons that would be able to tackle the present and future German heavy tanks.

The Next Generation of Soviet Self-Propelled Guns

1943 was a difficult year for the Red Army’s armoured forces. The early freeze on technological development in favour of mass production of existing designs meant that the latest Germans tanks now outclassed the static Soviet designs. The T-34 had barely evolved in two years of fighting, while its German equivalent, the Panzer IV, was now much more heavily armoured and equipped with a long-barrelled 7.5cm gun.

The new Russian vehicles that had been commissioned had yet to enter service, but as the year went on the balance inexorably began to creep toward the Soviet Union. By late war, 1944 onward, the technology of the two armoured forces was much closer to even.

Right: The SU-152 heavy self-propelled gun. Called the Big Game Hunter or Zookeeper, the SU-152 was an effective antidote to the German Tiger and Panthers tanks.

SU-152
Panther knocked out by a 152mm gun

Left: Mess with the best, go down like the rest. Note the size of the hole in the Panther’s hull from the 152mm APHE shell - that’s why the SU-152 is called a ’Big Game Hunter’. The hole in the turret is a 57 to 76mm hit.

One new weapon that entered service in mid-1943 was the SU-152 (called “Svierboy” or Big Game Hunters in reference to their role of stopping the heavy German ‘cats’).

This was the 152mm ML-20 gun-howitzer mounted on a KV-1s hull. 704 were produced, but only a single regiment (6 batteries of 2 SU-152) was available in time for the battle of Kursk. The 152mm gun-howitzer fired a massive Armour Piercing High Explosive (APHE) shell that would smash any tank in existence at the time. The weapon was relatively low velocity, which meant that at long range the shell would be ‘dropping’ onto the enemy tank (because of the curved trajectory of the round) and ploughing through the thinner armour on its deck. At closer range the kinetic and explosive energy of the shell could rip the turret clean off a tank. But the downside of this power was a low rate of fire and limited ammunition capacity (only 20 rounds were carried in each SU-152).

In August a new SP gun, the SU-85, went into production. This vehicle was based on a T-34 hull and was intended to replace the SU-122 in the medium SU regiments. The SU-85 mounted the 85mm D5 gun (the same as in the T-34/85) and was a more effective dual-purpose weapon than the howitzer carried by the SU-122.

Approximately 2050 SU-85s were produced until October 1944, when the next evolution of the medium SU concept, the SU-100, began to enter the assembly lines. The SU-100 mounted one of the best anti-tank guns of World War Two, the 100mm D-10S, and 1675 were produced by the end of the war. 

A SU-85 battery liberating Soviet citizens from foreign oppression
ISU-152 With the development of the new Soviet heavy tank, the IS-2, a complementary range of assault gun were built on the new tank’s chassis – the ISU-122 and the ISU-152. These replaced the now defunct KV-based SU-152. The design was originally meant to be just a 152mm armed vehicle, but there was a shortage of 152mm tubes, so the 122mm gun was mounted as well. Even when 152mm gun production got up to speed, the 122mm variant was considered so effective that it was retained in production.

Reports suggest that the troops at the front-line preferred the 152mm version because of its greater high-explosive hitting power.

Right: Based on the chassis of the IS-2 heavy breakthrough tank and mounting a 122mm D-25 gun, the ISU-122 posssessed fearsome hitting power.

 

Soviet Self-Propelled Gun Stats 

ISU-122

First Generation 

SU-76M
Weight: 11.2
Crew: 4
Armament: 76.2mm ZIS-3
Ammunition: 60 rounds
Armour (hull): 25mm
Produced: 12,671

SU-122
Weight: 30.9
Crew: 5
Armament: 122mm M-30
Ammunition: 40
Armour (hull): 45mm
Produced: 1,148

SU-85
Weight: 29.6
Crew: 4
Armament: 85mm D-5-S85
Ammunition: 48
Armour (hull): 45mm
Produced: 2,050

SU-152
Weight: 45.5
Crew: 5
Armament: 152mm ML-20
Ammunition: 20
Armour (hull): 60-75mm
Produced: 704

Second Generation

ISU-152
Weight: 46
Crew: 5
Armament: 152mm ML-20
Ammunition: 20
Armour (hull): 90mm
Produced: 4,075 (ISU-122 and ISU-152)

ISU-122
Weight: 46
Crew: 5
Armament: 122mm D-25
Ammunition: 20
Armour (hull): 90mm
Produced: 4,075 (ISU-122 and ISU-152)

SU-100
Weight: 31.6
Crew: 4
Armament: 100mm D-10S
Ammunition: 34
Armour (hull): 75mm
Produced: 1,675

Soviet Ammunition

Left: Ammunition is good. The two items at the right are the shell and powder charge for the 122mm gun in the ISU-122. To the left of those are the one-piece 85mm round, then the 76.2mm shell, followed by a 57mm sub-calibre round. The last three rounds are less than 20mm.

Self-propelled Artillery continued

"The shell cut the right part of the commander’s cupola. I was not beheaded because I had bent down to light my cigarette. Suddenly the Russian assault gun appeared and I gave an order to the gunner to open fire. Kramer shot, and a second shell, from another assault gun, hit in the turret. I can not remember which way I left the Tiger. The head phones-the only thing I have from my destroyed Tiger".
Otto Carius, German Tiger commander. 

Organisation of the SU Batteries

The SU (which means Samokhodnaya Ustanovka or self propelled mounting) regiments were divided into three types: light, medium and heavy. The organisation of these three types of assault guns varied according to the period of the war.

Some of the earlier shtatniy (the equivalent of the US Table of Organisation and Equipment (TO&E) or the German Kriegsstaerkenachweisung) were products of having only a limited number of vehicles in service, and later they were expanded as production increased.

However, the guns themselves were usually in four gun batteries, just like the towed artillery. The batteries were grouped into regiments. 

Right: A battery of SU-76s prepare to warm things up in the depths of the Russian winter by pounding fascist positions.

When they first appeared the SU-76 and SU-122 were grouped into mixed regiments of 2 medium batteries (each 4 SU-122) and four light batteries (each 4 SU-76). This did not prove to be a very successful arrangement as the two vehicles had widely varying characteristics and methods of operation. A few months later they were separated into a light regiment containing five batteries of four SU-76, and a medium regiment, which had four batteries of four SU-122. The SU-122 was replaced by the SU-85 in these regiments towards the end of 1943. Late in the war the SU-85 was in turn superseded by the SU-100. 

A battery of SU-76s

When the heavy SU-152 arrived in 1943 it was organised into a regiment of six two-gun batteries with a KV-1s as the regiment’s command vehicle.

In Late-war, the medium and light regiments were similar, but the mediums had five batteries of four now, like the light formations. The amount of supporting arms in the regiment was increased – notably the addition of an anti-tank rifle and a submachinegun company to each regiment. The infantry was intended to work in close cooperation with the guns to protect them from Panzerfaust equipped German tank-hunter teams. The tank formations had already received these detachments in ‘43. 

With the mass production of the ISU series reaching the front line, the heavy regiments were expanded to five batteries each of four ISU-122 or ISU-152. 

Not even the mighty King Tiger stands up to 122mm armour piercing shells! In May 1944 the Rifle Divisions received their own light SU regiments, these having three four-gun batteries of SU-76, with one additional SU-76 or T-70 as the command vehicle.

In late-war a larger formation was created. The SU brigade consisted of three SU regiments grouped together (60-65 guns). There would be SU-76 or SU-57 in the light regiments, or SU-100 in the medium regiments. The medium SU Brigades were formed from November 1944, a couple of months after the German Kingtiger heavy tank was first encountered, and would seem to be a response to the threat that the new enemy tank represented. A formation of 65 SU-100 would be a very effective counter to even a beast as powerful as the massive Kingtiger!

The Tactics of Soviet Self-propelled Guns

The Red Army was always very clear about how its self-propelled artillery was to be used, and it was distinct from how the Germans used their Sturmgeschutzen. The Soviet vehicles were always self-propelled artillery – not assault guns like the Germans had. The Soviet guns were intended to be the used in the same manner as any other direct fire artillery – they move into position and shell the enemy positions just like the crew of a towed 76.2mm ZIS-3 might. They were not intended to move up and participate in close-assaults like tanks or the German StuG III would.

ISU-122

A sign of this intended mode of tactical operation is the lack of a machine-gun on Soviet self-propelled guns. A machine-gun is very necessary if the vehicle is going to move close to the enemy to defend from opposing infantry.

The Russians were well aware of this; they had seen what had happened to the German Ferdinand assault gun at Kursk in 1943, for example.

But it wasn’t till very late in the war that the ISU series began to receive a 12.7mm AA machinegun (and this is of limited use as to fire it the commander must open the hatch and risk being shot!).This lack of a close-in self-defence weapon only makes sense if the vehicle is not intended to get close to the enemy.

German assault guns, on the other hand, were usually equipped with a machinegun, and it could often be operated from within the tank.

What the Soviet guns were intended to do is sit back and support the assault with direct artillery fire from overwatch positions on the flank and/or on higher ground. Direct fire allowed the shells to be placed exactly where they were required, with devastating effect. The heavier calibre weapons mounted on the SUs allowed them to destroy enemy anti-tank guns from beyond those enemy guns effective range. This had been the case with the SU-76, whose gun was intended to outrange the German Pak38 5cm. But as the Germans switched to heavier guns, the job of the SU-76 crew became more dangerous.
SU-76M

Even though the SU-85 and SU-100 were excellent anti-tank weapons they were never designated as tank-hunters (or Panzerjaegers in the German army) but were always called self-propelled artillery. However, an increasing number of anti-tank artillery brigades did have an SU-85 or 100 regiment attached, so the proportion of Soviet anti-tank defences that was self-propelled and armoured went up as the war progressed.

An SU-85 captured and put into service with the German army An interesting point about Red Army self-propelled guns is that each vehicle had a radio. This was rare in the tank arm – most tanks had no radio early in the war, and often only a radio receiver (not a transmitter) late in the war. Only lend-lease tank regiments had radios in each vehicle. Because of this, the SU batteries were able to act in a very coordinated manner and could manoeuvre independent of each other. For example, sometimes the battery commander would sit back and observe the target and coordinate the other guns as they advanced upon the enemy.

Focus on the ISU-152 and ISU-122

The Red Army had a policy of developing a self-propelled version of whatever tank they had. When the KV heavy tank series was replaced by the Joseph Stalin (IS) series in 1944, the KV-based SU-152 gun was replaced with the new ISU series, based on the IS Stalin hull.

This vehicle was originally intended to be armed with the same 152mm howitzer mounted in the SU-152. 

ISU-122 crossing a river on a pontoon bridge
However, there were production shortfalls with the 152mm tubes, so the 122mm A-19 Corps gun was fitted to some vehicles. This was because there was a large production base available for the 122mm gun as well as huge supplies of ammunition. Even when there were sufficient supplies of 152mm weapons available, the 122mm variant of the ISU was kept in production as it had proved itself very effective on the front line.

Originally the two versions used the same mantlet, but a modernised version of the 122mm gun was developed, called the D-25S, and this used a new, more rounded mantlet.

The ISUs proved so effective that more of them were built than the original IS-2 tank upon which there were based (4,075 ISU-122/152 versus 3,845 IS-2)!

ISU-122 moved through a city

The ISUs were slow but powerful beasts, designed for breakthrough operations. That is, assaults against heavily defended enemy lines. They were not well suited to the exploitation of the breakthrough – a task left to the T-34 crews!

One downside of such powerful armament was a limited ammunition supply and low rate of fire. The ISU-152 only carried 20 rounds of the massive, two-piece ammunition. The shell weighed from 43.6 to 49kgs, (96 to 108 pounds) and the powder charge was another 6kgs (13 pounds). Imagine spending all day loading that into the breech of a gun inside a hot, smelly and smokey tank!

The 122mm round weighed 25kgs (55 pounds) and the ISU-122S could carry up to thirty of them. The ISU series counted two loaders amongst its five crew members to help relieve the burden of loading these massive guns. 

As the ISUs were artillery pieces first, they primarily carried High-Explosive Fragmentation (HE-Frag) rounds. A maximum of only one third of their ammunition would be armour piercing. However, with an explosive round of the size that these beasts were throwing around, sometimes armour piercing ammunition wasn’t needed to knock out a tank. An HE-Frag shell could concuss the enemy crew, smash vision ports or destroy the running gear without penetrating the vehicles armour.

Soviet tests found that the 122mm round could knock out a Panther frontally at up to 2,500 metres.

Tank riders on a ISU-152
This kind of hitting power now in the hands of the Red Army reduced one of the primary design reasons behind the Panther. The Panther was designed primarily as a long-range sniper tank, intended to destroy large numbers of T-34s at beyond the range they could effectively hit back. This is why it had heavy armour on the front, and relatively thin on the side – the Panther wasn’t intended to mix with the enemy at close range, unlike the Tiger. The Panther initially did this job very well, but as the war progressed the Red Army had more and more weapons that could effectively return fire at long range, thus rendering the Panther increasingly vulnerable, but still highly expensive to make. Of course the German army still enjoyed a considerable advantage in hitting at long range because of their superior optics, but with 90mm of armour sloped at 60 degrees, the ISU series was capable of taking a few hits back! The 122mm round also proved highly effective against King Tigers.
Husband and wife ISU-122 crew

Left: Husband and wife ISU-122 crew. Guards Lt. Vera Orlova in command, while Guards Lt. Nikolai Orlov is the driver. This poor guy probably got nagged all through World War Two. Hullo, war crimes alert...  ;-)

Famous Red Army tank commander Dimitry Loza recalls how an ISU-152 attached to his Sherman-equipped unit was called upon to take out a Panther while engaged in street fighting in Vienna, 1945:

“But the solid-shot on the JS was so powerful that one hit was sufficient for anything. When we went into Vienna, they gave us a battery of heavy JSU-152s, three of them. How they held us back! On the highway we could make 70 km/h with our Shermans and the JSUs barely moved. When we got into Vienna there was an incident that I described in my book. The Germans counterattacked us with several Panthers. The Panther was a heavy tank. I ordered an JSU to move forward and engage the German tanks. "Well, take a shot!" And oh, did it shoot! I must say that the streets in Vienna were narrow, the buildings tall, and many wanted to watch this engagement between a Panther and an JSU. They remained in the street. The JSU let loose and the impact knocked the Panther backward (from the distance of 400-500 meters). Its turret separated from the hull and landed some meters away. But as a result of the shot broken glass fell from above. Vienna had many leaded-in windows and all of these fell on our heads. To this day I blame myself that I did not foresee this! We had so many injured! It was a good thing that we were wearing helmets, but our arms and shoulders were all cut up.” 

Plans were developed to mount even heavier guns in the ISU. Report were coming in from Soviet intelligence that the Germans were working on a new range of super heavy tanks, and the Soviet High Command had recently met the King Tiger. In the event the rumours about new heavy tanks turned out to be overstated, and the Germans couldn’t produce the King Tiger insufficient numbers to make it a real threat, so none of these vehicle were produced during the war. If those vehicles had seen action they would have met the ISU series uparmoured and upgunned with long barrelled 152mm guns (the BL-8 and BL-10 guns), and a version armed with a modified naval gun – the 130mm S-26 firing a 33kg (72lb) shell at 900 metres per second (compared with the 122mm 25kg (55lb) shell at 780 metres per second). In other words the Red Army already had plans in place to stop any German tank developments, and the German belief that heavier and heavier tanks would win them the war was really just a fantasy.

After the war the ISU series continued to be used by the Soviet Union and her allies, and became the basis for a number of very heavy gun mounts (including a 406mm gun and a 420mm mortar!). The ISU series remained in production until 1955.

Stay tuned for part three in which we look at Soviet anti-tank guns! (live 1 January 2009)


Last Updated On Friday, July 31, 2009 by Wayne at Battlefront