Did the KV-85 heavy and T-34/85 medium tanks, which entered service in the war on the Russian Front, show up around the beginning of 1943 or much later at the start of 1944? Marshal Georgi Zhukov boasted in his memoirs, “By the summer of 1943, before the Battle of Kursk, the Soviet armed forces were superior to the German Fascist forces both quantitatively and qualitatively.” Other scholars think the tanks took a later road into battle. David Glantz and Jonathan House, authors of When Titans Clashed: How the Red Army Stopped Hitler (1995), wrote that “Soviet designers began to upgrade the workhorse T-34, giving it an 85mm gun in place of the 76.2mm; however, this change did not occur in time to help the Red tankers at Kursk.”

The disagreement could seem a pointless squabble over minutia, but the answer to the question reveals much about the war on the Russian Front. If the traditional view is taken that the KV-85 and T-34/85 were introduced prior to the epic armored battle at Kursk, then the Soviets equalled or bettered the technological advances of the Germans. On the other hand, if the revised view is correct, then Soviet tank designs fell behind the Germans soon after the beginning of the war and remained so for the duration. This interpretation requires us to accept an unusual timeline that has the Soviets taking more than 45 months (December 1939–September 1943) to make the leap from 76mm to 85mm guns on the production KVs, but then miraculously needing only 16 weeks to leap from a Klimenti Voroshilov tank equipped with an 85mm gun to the even more formidable Josef Stalin tank with its 122mm gun.

Armored enthusiasts accept that the KV-85 preceded the T-34/85. Earlier variants of both the KV heavy and the T-34 medium tank were in service when the German invasion began, and both were later upgraded to heavier caliber guns as the war progressed. What remains unresolved is which KV preceded the T-34/85 and when that vehicle was produced. Recent scholars assert that it was the KV/Josef Stalin hybrid that immediately preceded the Stalin at the end of 1943. This cannot be the case. The larger turret required to house the heavier gun found in the Stalin tank could not have fit in the smaller KV chassis. Others have discovered, however, that the turret developed for the heavier tank could be fitted to a KV-1 chassis by increasing the diameter of the KV’s turret ring and adding a pair of fillets to either side of the hull. According to historians Steven Zaloga, Jim Kinnear and Peter Sarson, the new turret, dubbed the D-5T, went into production in September 1943 and 130 were added to up-gunned KV-85s. According to Terry Gander, however: “It [the T-34] had a new 85mm gun mounted in a cast steel turret originally developed for the KV-85 heavy tank. The rest of the tank was virtually unchanged from the original T-34/76.”

It seems unlikely that even a modified version of the D-5T turret from the KV/Stalin hybrid could have been simply dropped onto a T-34. The T-34 hull is 13 inches narrower than the Stalin’s, and its distinctive angular shape would have made modification to fit the heavier tank’s turret an engineering challenge of the first order. If the T-34/85 hull was “virtually unchanged” from the T-34/76, then the turret made for the 50-ton Stalin is just too big and heavy to be part of the 35-ton T-34/85.

Zaloga, Kinnear and Sarson wrote that “A total of 1,370 KV-1S were produced through April 1943, when KV production finally ended in April 1943 in favor of the T-34.” According to them, the T-34 was produced for five months before the factories switched back to KV-85 production in September-October 1943 just prior to production of the Stalin tank.

It is improbable that the Soviets produced 130 of these KV hybrids with new KV-1S hulls, Josef Stalin turrets and 85mm guns. Such a production feat would have required a nation fighting for its life to have retooled its factories for the KV-1S in August 1942, retooled again for the T-34 in April 1943, and retooled yet again for the KV-1S hulls in September 1943—with a further retooling for the Stalin a month later. Then they would have had to modify each and every one of the later KV-1S production hulls for the large turret ring and add the fillets. It would have been far easier and more efficient for the new hulls to be redesigned to accommodate the large turret ring before re-entering production.

What, then, explains the rapid changeover in type and designation of vehicles? Zaloga, Kinnear and Sarson provide a clue: “It is difficult to characterize these many variations as the Red Army did not codify them with elaborate designations like those employed by the Wehrmacht’s Waffenamt,” and, they assert, “They made scanty use of the rough model/year designation system, and with little regularity.”

Problems with codification may have caused the KV/Stalin hybrid to be reported as the production model KV with 85mm gun that preceded the T-34/85. The hull of this later version could never have been produced in quantity. Most likely it was either part of a program to update some surviving KVs to the Stalin standard, or one of a few prototypes made for testing the new heavy tank’s components. Given that it is unreasonable for the KV’s production to have been restarted to manufacture a mere 130 units, then these hybrids must have been built by mating recycled KV-1S hulls with new Stalin turrets.

The predecessor to the T-34/85, a “missing link” in the story of Soviet armored development, had its origins with the KV-1S, a lighter variant of the KV heavy tank. Five tons had been cut from the weight of the KV simply by giving the vehicle a much smaller turret. But while the new turret could mount the heavier 85mm gun, the crew didn’t have enough room to operate it efficiently. The smaller turret could, however, be mounted on a T-34 chassis. The source for what became the T-34/85’s turret was the KV-1S/85, since it has the smallest KV turret and was the only other prototype that is known to have existed at the correct time.

A comparison of a prototype and a production model of the KV-1S/85 is illuminating. The production model has the heavy barrel and bulging rounded mantlet found on the prototype but with a slightly shorter barrel that could easily be confused with a 76mm of similar length. Another difference between the two tanks is revealed in the road wheels, which can help determine the date of construction. The hull shape and road wheels of a KV-1S prototype on exhibit at the Kubinka Museum in Russia indicate it was manufactured around August 1942.

As early as the spring of 1941, Deputy People’s Commissar of Defense Marshal Grigory Kulik had convinced himself that the Germans were working on a new heavy tank that featured 100mm armor and a heavier gun. In fact, just before the start of Operation Barbarossa, a hard-hitting heavy tank went into development at the Henschel firm in Kassel, Germany, that would eventually become the Tiger I. The knowledge Kulik possessed allowed the Soviets about 15 months to develop vehicles of their own to counter this emerging threat.

As soon as the Tiger Is of the 502 Heavy Tank Battalion made their operational debut on August 29, 1942, at Mga near Leningrad, the Soviets responded by rushing their most advanced prototype, the KV-1S/85, into production in September, building up to 1,370 of them. The KV- 1S/85 is significant because its components were used in two of the most important armored vehicles produced during the war: its turret in the T-34/85 and its hull in the SU-152. Production of the T-34/85 began in March 1943, at about the same time that the KV-1S/85 was discontinued. The light turrets, with their more potent armament, combined with the sloping armor and small frontal area of the T-34 hull, resulted in a vehicle that gave protection nearly equal to that of the heavy KV but was several tons lighter, with a cross-country speed sufficient to keep up with older T-34s. Its gun was powerful enough to penetrate the frontal armor of the Panther and Tiger at long range.

Two KVs were mounted with an 85mm gun: the KV-1S/85, made around August 1942 at the beginning of the KV-1S production, and the KV/JS-85 hybrid, made about a year later. That means that the Soviets had at least 10 months to develop and produce the T-34/85 before the commencement of the battle at Kursk. This remarkable fighting vehicle got to the battlefield in time because the T-34/85 was not completely new but a combination of off-the-shelf parts already in production. Both the KV-1S/85 and T-34/85 were almost certainly produced in quantity before the middle of 1943, and significant numbers of each were present at Kursk in July. The Soviets’ success in meeting anticipated threats on the battlefield illustrates the sentiments shown by armored officer Colonel Gary L. Parrish, who said, “When confronted by the reality of defeat, a nation will modify systems in their inventory to meet the challenges of their adversaries.”


Originally published in the August 2006 issue of World War II. To subscribe, click here