Comparing: ISU-122S vs. E 25

A heavy assault gun, built on the basis of the IS tank, was effective against German heavy tanks as well as fortifications. The prototype was built at the Chelyabinsk Kirov Plant in April 1944. The vehicle entered service in August of that year, and a total of 675 vehicles were manufactured in 1944 and 1945.

The development of the E 25 was part of the "E" program, supervised by the Waffenprüfamt 6 committee. The E 25 was developed by the Argus company (Karlsruhe, Germany) under the supervision of Dr. Herman Klaue. No prototypes were manufactured.