Comparing: KV-3 vs. KV-4 vs. IS-3

Developed on the basis of the KV heavy tank, the vehicle initially had very few differences from the mass-produced model. It underwent field trials in January–February 1941. Eventually, several crucial changes were made to the design, greatly boosting the combat characteristics of the vehicle. By July 22, 1941, chassis and engine development was completed. According to some sources, in the fall of 1941, the vehicle was equipped with a serial KV turret and sent to the front.

The project of N. L. Dukhov developed in April 1941. A prototype was to be produced by November 1941. However, the work was discontinued due to the outbreak of the Soviet–German war.

Mass production of the vehicle started in May 1945. On September 7,1945, IS-3 tanks took part in the Allied Victory Parade through Berlin. A total of 1170 vehicles were manufactured by the end of 1946, when production was canceled. From 1948 through the late 1950s, the tanks underwent a number of modernization refits.