The Iosif Stalin tank (or IS tank, also known as the Joseph Stalin tank), was a heavy tank developed by the Soviet Union during World War II and first used in the Kursk area in September 1943. The tanks in the series are also sometimes called JS tanks.
The heavy tank was designed with thick armour to counter the German 88 mm guns, and carried a main gun that was capable of defeating the German Tiger and Panther tanks. It was mainly a breakthrough tank, firing a heavy high-explosive shell that was useful against entrenchments and bunkers. The IS-2 was put into service in April 1944, and was used as a spearhead in the Battle of Berlin by the Red Army in the final stage of the war. Ingame we have nine IS variants: IS-1, IS-100, IS-2, IS-3,IS-3/D-30, IS-4, Object 701-1, Object 701-3 and OTIS-4.
The IS-3 was developed by the Soviet Union and was the successor of the famous IS-2. Both share the same cannon, the TSh-17 gunsight and suspension. The main difference is the improved armour layout, and a hemispherical cast turret (resembling an overturned soup bowl) which became the hallmark of post-war Soviet tanks. The IS-3 came too late to see action in World War II. Though some older sources claim that the tank saw action at the end of the war in Europe or Manchuria, there are no official reports to confirm this. These vehicles took part in the Berlin Victory parade of 1945 at 7 September 1945 (video) in the amount of 52 pieces , where they made a strong impression on the Western allies of the USSR.
This variant carries the powerful D-30T cannon which was initally thought as a main weapon for the IS-6.
In FHSW it is also equipped with a mechanical loading system which makes it fire around 1.5 times faster than the regular IS-3. The fire power of the cannon is only slightly better than the standard 122 mm D-25 gun though.