Soviet Heavy Tank IS-1 (Iosif Stalin - 1)
The need of mightier than KV tank arose because of higher effectivity of
German anti-tank defense and awaited appearing of new vehicles Tiger and
Panther. In the beginning of December, 1943 the mass production of IS-1
or IS-85 has begun.
Tank was equipped with 85mm half-automatic cannon constructed by
F.F.Petrov and its weight was a little more than of KV-1S, but had
thicker armour. Its width was also 18cm lesser than of KV-1S due to
installation of smaller turning mechanisms constructed by A.I.Blagonravov.
But after the beginning of IS-1 production the question of strengthening
heavy tank's armament was not answered. T-34-85 had also 85mm cannon
installed. It was not very wise to have medium and heavy tanks with the
Soviet Heavy Tank IS-2 (Iosif Stalin - 2)
The tank with the new 122mm tank half-automatic cannon also constructed
by F.F.Petrov goes to the mass production at 31th December, 1943. IS-2
Thanks to good costruction the size of IS-2 was not increased in
comparison with KV, but the speed and manoeuverability were higher. The
vehicle was easy to drive and was easy to repair at field conditions.
At the 500m range the cannon shell pierced armour up to 140mm thick. IS-2
first battle was at Korsunj-Shevchenskij in February, 1944, where it
shows its excellent combat abilities.
Before the end of war, IS-2 was modernizated. In the second quarter of
1944, tank received better targeting instruments and larger cannon armour
mask. From the middle of 1944 had the same form of hull as T-34's one.
Tank was named IS-2M.
Soviet authors said that IS-2 was the mightest tank of the Second World
War and that the German command ordered its tankists to avoid the open
duels with IS-2.