On September 7th 1945, the allied nations were staggered by Russias disclosure of their JS-3 heavy tank at a victory parade in Berlin. Although coded a JS tank, it had a totally different appearance from its preceding models. The one-piece cast turret had a simple flattened hemispherical shape. The maximum thickness of the turret armor reached 250mm. The front hull was constructed by welding three 120mm thick armor plates, forming a shape like a ships bow. The main armament used the same L43 122mm gun as the JS-2. The 520 horsepower diesel engine provided 40km/h of maximum speed. With the concerted effort of the talented Russian tank engineers such as N.L. Jukhov and Z.A. Kotin, the prototype was completed in October 1944 and the mass production began in the following year.