The Technological Imperative Revived
The 1942 defeat at Stalingrad was the high water mark of the German advance on the Eastern Front. Although often called the turning point of the war, Germany retained the strategic initiative until the battle of Kursk in the summer of 1943. Technically, the Soviet tank force in the summer of 1943 was not significantly different from its condition in mid-1942. By now, the Soviet factories were turning out T-34s in increasing numbers, and it had become the staple of the Red Army's tank and mechanized corps. It was still armed with the same 76mm gun as in 1942 and protected by the same level of armor.
The KV-1 had proven a dissappointment in 1942. It lacked 'firepower' advantage over the T-34 and its armor was no longer invulnerable to German antitank weapons as it had been in 1941. Its weight caused tactical mobility problems without conferring relative invulnerability, and it was plagued by lingering technical problems, especially poor transmission. As a result, its armor thickness was actually reduced in 1942, and the KV-1 was removed from the tank corps and segregated into separate tank regiments for infantry support. A portion of the production lines at Chelyabinsk shifted to T-34 production and consideration was given to ending heavy tank production completely in favor of the T-34.
In the area of light armor, the T-60 light tank was being joined by the modestly improved T-70 light tank. Both types would have dissappeared but for the fact that their factories did not have heavy machinery capable of turning out T-34s. The main improvements in the Soviet armored force in 1942 were tactical, not technical, particularly the maturation of the new tank and mechanized corps. In June 1942, the Red Army authorized the development of a "universal tank." The idea was to combine the better armor of the KV with the superior mobility of the T-34; the tank gun remained the same. The universal tank would replace both the T-34 and the KV-1. The heavier armor was necessary as the advent of the German long 75mm gun in May 1942 had made the T-34 vulnerable for the first time to the standard German tank at normal combat ranges.
Two designs were competitively developed in Nizhni-Tagil and Chelyabinsk, an uparmored and improved T-34 called the T-43, and a reduced-weight KV called the KV-13. While the idea of standardizing on a single, universal type was desirable, the focus on armored protection proved to be a mistake.
The T-43 or KV-13 might have entered production in the summer of 1943 but for the arrival of excellent new German tanks. Tiger Is were encountered in small numbers on the Leningrad front starting in January 1943 and one was promptly captured by the Soviets and examined. Although clearly superior to the KV in armor, mobility and firepower, few were encountered in combat before the summer of 1943.
But during the battle of Kursk in June 1943, the Germans introduced the first Panthers, and the numbers of Tigers dramaticaly increased. The Panther had been specifically developed to deal with the T-34 and was intended to become the standard tank of the German armored force. Soviet tank formations were decimated at long ranges in many lop-sided encounters. For the first time during the war, tank panic set in among the Soviet units, and the tank force demanded tanks with "longer arms" to be able to deal with the new German designs.
The priority assigned to Soviet tank production was clearly needed given the Soviet rates of loss, but it distracted the tank design bureaus from preparing for technological improvements by the Germans. The inadequately armed "universal tank" requirement indicated that the Soviets did not anticipate the German shift towards heavier, better armed tanks and were unprepared with a new tank gun capable of dealing with them.
This failure by the Red Army bureaucracy helped give more influence to the tank designers who had been pushing for larger guns, a traditional preference that had been suppressed by the production managers from 1942 to 1943. A crash program was instituted in the late summer of 1943.
A new 85mm tank gun, derived from the 85mm anti-aircraft gun, was adapted into a new three-man turret for the T-34-85. This ignored the increased armor sought on the T-43 universal tank, but did recognize the command deficiencies of the earlier T-34s. This tank entered service in small numbers in February 1944 as the T-34-85, and proved an immediate success. Although its gun was not as effective as either the Panther's long 75mm gun or the Tiger I's 88mm gun, it restored a measure of balance in the technolgical arms race since it could defeat either tank under the right circumstances. Furthermore, being based on a virtually unchanged T-34 chassis, it did not upset production to the extent that the costly new Panther had upset German industry.
The KV tank was substantially redesigned after its poor showing at Kursk in 1943. Had the Soviets allowed the KV-3 to replace the KV-1 as planned in 1941, it would have remained viable and could have served as a counterweight against the Tiger and Panther at Kursk. The Red Army was still concerned about the vulnerability of the new T-34-85 to enemy tank fire, and desired to have a heavy tank that was less vulnerable to enemy antitank guns.
There was a clear recognition that such a tank could not replace the T-34 because it placed greater demand on industrial resources, and so a mix of medium and heavy tanks was continued.
Due to the temporary disgrace of the namesake of the KV tank, Marshal Kliment Voroshilov, in the 1941 battles, the evolutionary improvement was renamed the IS (Joseph Stalin) heavy tank. It was derived from the cancelled KV-13 universal tank, but it retained the KV's longer hull. The most pressing issue was the matter of armament.
The capture of the German Tiger tank in January 1943 led a series of ballistic trials against the captured tank. The Tiger was subjected to fire from 76mm tank guns using new ammunition, from 122mm howitzers, 85mm antiaircraft guns and 122mm corps guns. Both the 85mm antiaircraft gun and 122mm corps gun gave good performance against the Tiger, and there were hopes that new antitank projectiles could further improve their performance.
The effort to adapt the 85mm antiaircraft gun to tanks was handed over to General F. Petrov's artillery design bureau in Sverdlovsk. As a stopgap, the 85mm gun was installed on a modifed KV-1 tank called the KV-85, and about 130 were completed at Chelyabinsk in September, 1943. The heavy tank design bureau in Chelyabinsk was apparently unaware that the T-34 design bureau in Nizhni-Tagil was already working on adapting the same gun on to the T-34. This would lead to the same imbalance as before with both the T-34 and the new heavy tank being armed with the same weapon.
Firing trials of the new D-5T 85mm gun proved disappointing. Several captured German Tiger I tanks were shipped to Chelyabinsk, where they were subjected to 85mm fire from various angles. The 85mm gun could not reliably penetrate the Tiger I except at ranges well within the lethal envelope of the Tiger I's own 88mm gun.
The solution was to mount a heavier gun in the new IS tank. Petrov's bureau favored the new D-10 100mm gun being developed by his bureau specifically for tank fighting. (This gun would later arm the SU-100 tank destroyer and the T-54/T-55 rank.) However, it was unlikely to be ready in time, and ammunition supply would also be a problem since it represented a new gun caliber for the Red Army.
Ammunition for the 122mm corps gun was already in the Red Army's supply network, and there was surplus industrial capacity for the 122mm gun, so this weapon was selected. This project was approved in November 1944, just after the first batch of IS-85 tanks with the inadequate 85mm gun were coming off the production lines. A total of 67 IS-85s were completed by the end of 1943 and 40 more at the beginning of 1944, but nearly all were rearmed with 122mm guns before being issued to the troops. Production of the new version with the 122mm gun, called the IS-2, began immediately afterward in January 1944.
The Soviet selection of the 122mm gun for the IS is illustrative of Soviet tank design philosophy during the war. Unlike the Germans, who were willing to incur a continual string of production and logistics difficulties to acquire modest firepower, mobility and armor advantages, the Soviet designers were forced to compromise in order to ensure ease of production, high production rates, and logistical harmony with the supply system.
This experience was not unlike that faced by US tank design in World War 2. It was only in late 1943, with the war turning clearly in favor of the USSR, that the heavy tank designers were allowed to bring their costly new tank to the production stage. Even then, the design contained many common elements with the previous KV tank, including a very similar engine, a common track and many other identical components.
Soviet light tank production was abandoned after Kursk. There were several reasons for this. To begin with, light tanks, armed with 45mm guns, were inadequate in tank fighting or infantry support due to their poor firepower. This view was shared in many other armies of the time. The US Army, for example, abandoned the 37mm armed M5A1 light tank for the 75mm armed M24 in 1944 for much the same reason.
Secondly, continued needs for light tanks for reconnaissance units were being fulfilled by Lend-Lease supplies of Canadian Valentine tanks, which became the predominent light scout tank in Soviet units in 1944. Finally, the industrial resources allotted to the T-70 were better used building a light assault gun version of the T-70, armed with the 76mm ZIS-3 divisional gun, the SU-76M. Indeed, the SU-76M became the second most common Soviet armored vehicles of the war (after the T-34). It was used in Soviet infantry units for close support, much like the pre-war T-26 light tank.
The Red Army was shipped 1,683 light tanks and 5,488 medium tanks from the United States; and 5,218 tanks from Britain and Canada under Lend-Lease. This amounted to 16 percent of Soviet wartime tank production. The Red Army held a generally disparaging view of Allied tanks, comparing them very unfavorably to the T-34. However, British and American light tanks were no worse than the T-60/T-70, and the M4A2 Sherman was not significantly inferior to comparable models of the T-34.
These tanks were widely used in Soviet units, and in 1943, about 20 percent of Soviet tank brigades were of mixed Soviet/Lend-Lease composition while about 15 percent were equipped entirely with Lend- Lease types. US and British tank design had little technical impact on Soviet tank design after the war except for some subcomponents, such as tank gyrostabilizers.
In contrast, US truck design was enormously influential, forming the basis for most post- war Soviet military truck design, and much of Soviet post-war automotive engine design. German tank technology had far more impact, particularly in engine, transmission and suspension design.
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