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Countdown to Bagration: the tanks of Bagration – Soviet ISU-152

by on August 25, 2012


The initial variant, developed in 1943. The factory designation was Object 241 (Объект 241). It was armed with the 152.4 mm ML-20S (МЛ-20С) gun-howitzer, with a barrel length of over 4.2 metres (27.9 calibers). The self-propelled gun carried 21 rounds of two piece (shell and charge) armour-piercing and high explosive ammunition. The gun had a maximum range of 6,200 metere. The armour-piercing round, weighing 48.78 kg, had a muzzle velocity of 600 m/s and a maximum penetration of 125 mm of RHA at 90° at a range of 500 metres. The ISU-152 had different modifications concerning the gun (newer modifications), the number of the hatches, or the hull, based on the one of IS-1, IS-2 or IS-2 model 1944. The latter modification had a thicker gun shield, fuel tankage with increased volume etc. Till May 1944 the main armament was the 152.4 mm ML-20 model 1937 gun-howizer. ISU-152 had a rate of fire of 2-3 rounds/min. The early modifications had three hatches at the superstructure roof and one emergency hatch at the bottom of the hull behind the driver’s seat, which had an armoured cover. Later was added a fourth, round hatch, at the superstructure roof on the right, next to the rectangular hatch on the left. The later ISU-152 modifications, with newer gun and slightly longer barrel, up to over 4.9 metres (32.3 calibers), had a maximum range of fire of up to 13,000 metres.


As a heavy assault gun, the ISU-152 was an extremely valuable weapon in urban combat operations such as the assaults on Berlin, Budapest and Königsberg. The vehicle’s excellent armour protection finally provided the 152.4 mm platform with good protection from most German anti-tank guns, allowing it to advance into the face of direct anti-tank fire, while the huge low velocity high-explosive rounds were excellent at blasting open even the most heavily fortified and reinforced enemy strongpoints. Such actions would be much more dangerous and much less effective for a conventional towed artillery piece, with their high crew exposure and low mobility, or even a tank, with their smaller main guns. When supporting tanks, the usual tactics of the ISU-152 were to be used in the second line of the attack order, 100 to 200 metres behind the attacking tanks, which were usually IS tanks with equal mobility.

The ISU-152, like the earlier SU-152 and contemporary ISU-122, was employed by Independent Heavy Self-propelled Artillery Regiments. Between May 1943 and 1945, 53 of these regiments were formed. Many of them were re-formed tank regiments, and employed similar direct fire tactics as used by tanks when supporting infantry. Each of the heavy regiment had 21 guns, divided into 4 artillery batteries of 5 vehicles and the commander’s vehicle. For support the heavy regiments had some supplementary unarmoured vehicles such as trucks, jeeps, or motorcycles. In December 1944, Guards Heavy Self-propelled Artillery Brigades were formed, to provide heavy fire support to the tank armies. They were organized along the model of tank brigades, each with 65 ISU-152 or ISU-122 self-propelled guns.


To minimize the risks of being knocked out by Panzerfaust-equipped units during urban operations, the ISU-152 usually acted in one or two vehicle detachments alongside infantry squads for protection. The infantry squad would include a specialist sniper (or at least a sharpshooter), some submachine gunners and sometimes a flamethrower. The ISU-152’s heavy calibre DShK machinegun was also useful for targeting Panzerfaust gunners hiding on upper floors of city buildings or behind protective cover, barricades, etc. Effective teamwork between the ISU-152 crew and supporting infantry allowed them to achieve their goals with minimal losses, but if such tactics were not adhered to, the attacking vehicles were easily attacked and destroyed, usually through the weaker armor on the roof or rear compartment.


The ISU-152 could also operate as an effective heavy tank destroyer. Though it was not designed for the role, the vehicle inherited the nickname Zveroboy (“beast killer”) from its predecessor, the SU-152, for its rare ability to reliably kill the best protected German fighting vehicles, the Panther tank, the Tiger and Tiger B tanks, and even the Elefant and Jagdtiger tank destroyers. The sheer weight of the 152.4 mm shells resulted in an extremely low rate of fire, only one to three rounds per minute, and were not as accurate at long range as high-velocity antitank guns. However, the massive blast effect from the heavy high-explosive warhead was capable of blowing the turret completely off a Tiger tank. A direct hit usually destroyed or damaged the target’s tracks and suspension, immobilizing it. While the low-velocity 152mm shell did not generally penetrate heavy armor, it frequently killed or severely wounded the crew through spalling (splintering) inside the hull as well as injuries caused by blast concussion. Surviving crew were often left with an immobilized vehicle which had to be hurriedly abandoned before being destroyed. For anti-tank operations following the Battle of Kursk, armour-piercing ammunition was developed, with an eye towards giving the howitzer a more traditional anti-tank capability. However, these rounds were expensive, in short supply, and only moderately more effective than the standard non-penetrating high-explosive round. As a howitzer the ML-20S exchanged velocity and accuracy for throw weight and distance, and was not intended to compete with true anti-tank guns. Sometimes the concrete-piercing ammunition was used for the anti-tank role. A primitive shaped charge ammunition, with a 27.44 kg shell, was also developed. It had a maximum penetration of 250 mm of RHA at 90°, but it was not used during the war.


The ISU-152’s 90 mm of sloped frontal armor, in contrast to the SU-152’s 65 mm, provided excellent frontal protection from the 75mm KwK 40 gun of the ubiquitous Panzer IV and StuG family at all but the closest ranges, while also forcing the original Tiger I, with its vaunted 88mm KwK 36 gun, to close to medium ranges in order to successfully penetrate the vehicle, negating its traditional long range superiority and exposing more of its vulnerable flanks to the 85mm ZiS-S gun of the Soviet T-34-85.


The ISU-152 was not a true purpose-built tank destroyer. It had a very low rate of fire compared with specialised tank destroyers such as the German Jagdpanther or the Soviet SU-100, which could manage a brief burst of 5-8 rounds per minute. However, prior to the introduction of the SU-100 it was the only Soviet armored vehicle capable of tackling the German heavy tanks with any kind of reliability, and its ability to satisfy multiple roles meant it was produced in far greater numbers than the SU-100. Attention to camouflage, quick relocation between firing positions, and massed ambushes of 4-5 vehicles firing in salvo at a single target’s flanks reduced the disadvantage of the low rate of fire. Using these tactics, the ISU-152 became greatly feared by German heavy tank commanders, robbing them of their prior sense of invulnerability to Soviet guns and forcing them to commit their forces more cautiously and sparingly.



From → Flames of War

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