The Eastern Front of World War II saw a constant spiral of increasing tank sizes, gun sizes and armor thickness. The largest allied tank to actually see widespread service during the war years, the IS-2 was built to be a Tiger killer.
Join me for a look at this Soviet giant.
The Soviets used heavy, or “breakthrough” tanks throughout the war. But by the mid-war period it was obvious their current family of heavies, the KV series, offered little advantage over the T-34 while costing considerably more to build. This especially caused concern for the design bureau responsible for the heavy tanks. So a completely new design was initiated. They started with the largest gun available in quantity, a 122 mm type. It was armored against all current German anti-tank guns. Perhaps its most significant upgrade would be the “IS” designation derived the Cyrillic initials of Joseph Stalin’s name.
The 122 mm main gun is an obvious feature.
This beast was only slightly smaller than the German Tiger and was developed at about the same time as the King Tiger. Both German tanks used 88 mm guns with higher muzzle velocity and better quality ammunition. But the 122 on the IS-2 had a bigger shell which meant more kinetic energy. The tank’s armor was also thicker in places, but of lower quality.
Automatic weapons are mounted curiously. There is no commander’s gun, and no bow gun. But there is a light mg in the back of the turret in addition to a co-axial gun in front.
The net result was a surprising level of parity. The King Tiger and IS-2 could reliably make kill shots on each other from 1000-1500 yds, while greater ranges posed increasing difficulties. The King Tiger was clearly a more sophisticated weapon, with better targeting optics for better performance at longer ranges. And German crew training and tactics were generally superior.
The overhang of the main gun is significant!
The IS-2’s bigger gun also had a very effective high explosive round that was useful in a wide range of operations, making it far more than just a Tiger killer. But the ammunition was so heavy that shells and powder were loaded separately, making for a much slower rate of fire. The IS-2’s biggest advantage was its cost and ease of production; the Soviets did much better getting large numbers into the field. For a thorough comparison I recommend King Tiger vs IS-2 by David R. Higgens.
Late war partners; an IS-2 and T-34.
As a “breakthrough” tank the IS-2 was expected engage in heavy combat at the front to force a breach. This would allow the much faster T-34 to penetrate into an enemy’s rear areas.
This example is from the Tamiya kit and represents a tank that fought in the Battle of Berlin.
The King Tiger is clearly bigger in every dimension except the main gun.
Plane Dave 
The Soviet tank was mass produced in large enough quantity to overwhelm the opposition. By the time this tank appeared German tank superiority had dwindled.
On a tactical level German armor was dangerous all the way to the end. But no doubt the IS-2 gave the Soviets a capable enough weapon in quantity.
Oddly the appearance of this tank caused the Germans to adopt flanking tactics similar to what the US used on the western front.
The choice of main gun is interesting. There was a 100mm gun with superior armor penetration, but there was a surplus of the 122 and it’s ammunition, while the 100mm was relatively rare.
Yeah that’s exactly what I’d read about the 122. The gun is so big it almost looks like something from Warner Brothers.
The summery of the analysis I read was that IS-2 vs King Tiger was close enough that one on one it was a matter of crew quality. Which normally favored the Germans. But it was almost never one on one because industry and manufacturing issues favored the Soviets.
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