IS4

The IS-4, named after Soviet leader Joseph Stalin, is a heavy tank developed by the Soviet Union in the late 1940s as part of the IS (Iosef Stalin) family. It was designed to provide increased protection and firepower for breakthrough operations and to counter heavily fortified targets encountered in the immediate postwar period. The IS-4 followed the IS-3 and incorporated lessons from late-war combat, including armor configuration, firepower, and crew ergonomics.

In design terms, the IS-4 featured a welded hull and turret with thick front armor, a heightened chassis for better armor compatibility, and a robust suspension suitable for heavy weight. The main armament was a 122 mm gun, capable of delivering high-velocity rounds with significant penetration. The crew typically consisted of four to five members, depending on configuration, and the tank employed a powerful engine and drivetrain intended to improve mobility for its weight class. The IS-4 used a torsion-bar suspension system common to Soviet main battle and heavy tanks of the era.

Production and service were limited compared with earlier IS models. The IS-4 entered production in the late 1940s and saw only limited deployment in the early Cold War period, with eventual replacement by later heavy designs such as the T-10 family. Some units remained in reserve for a time, and a few were preserved or evaluated in various allied or post-Soviet contexts.

Variants and modernization efforts were modest, with no large-scale production of upgraded IS-4 variants. The tank’s influence is primarily as a transitional design bridging late World War II-era concepts and later Cold War heavy-tank developments. Surviving examples are displayed in some museums.