Staff Writer (Updated: 2/7/2016):
The IS-3 was essentially a redesign of the IS series as a whole. The turret was given a new, well-rounded look while the glacis plate was more heavily sloped for better ballistics protection. Room for the turret crew was improved as was space for additional projectiles while not losing any of the critical armor protection the series had become famous for. In fact, the IS-3 showcased more armor protection across it turret than previous IS incarnations. Overall armor protection was as good as ever, providing relative safety to both man and machine. The new turret and hull design provided for a lowered silhouette, in effect making her a more difficult target to track from any angle. The powerful 122mm (121.9mm) primary armament was retained for its proven penetration capabilities at range with a skilled crew letting off between 2 and 3 rounds per minute. Projectile choices for the commander were broadened and included at least 10 armor-piercing (AP) rounds along with up to 18 high-explosive (HE) fragmentation rounds giving the IS-3 flexibility when engaging various battlefield targets.
The prototype appeared under the rather bland designation of "Object 703" in October of 1944. Within a short time, the prototype was evaluated and accepted for serial production to commence at Soviet factories equipped for the construction of heavy vehicles. The first examples of completed IS-3s arrived in the Red Army inventory in May of 1945. However, Hitler had already committed suicide at the end of April and the war in Europe was all but over - Berlin had fallen to the Soviet Army and the German war machine was dismantled to become a few remaining pockets still fighting on. The IS-3 was noted for its later appearance in the September 7th victory parade through Berlin proper.
However, while the war in Europe had closed, the Soviets were still continuing their war against the army of Japan in the Far East and it is believed that at least one regiment of the new IS-3 series was deployed in an unknown capacity during August of 1945. The Empire of Japan would, itself, officially capitulate by the end of the month, ending the war in the Pacific.
By the end of the war, the IS-3 proved to be the most advanced tank of its kind anywhere on the battlefield. Production continued through to the middle of 1946 to which some 2,311 individual examples were ultimately completed. The IS-3 went on to stock the inventories of the Red Army and Soviet allies for decades to come during the volatile Cold War years. Its design went on to influence all future Soviet tank endeavors for the next two decades with inquisitive eyes in the West even taking notice.