During the beginning of Operation Barbarossa, the Germans had little difficulty routing the Russian Army. The Russians were simply unprepared for the high quality tanks and troops of the Germans. German over-confidence ceased when they came up against the T-34. An extremely well designed and influential tank with its roots dating back to J. Walter Christie, an American inventor, this tank was extremely formidable. German armour simply could not compete with the excellently sloped armour, the high-velocity 76.2mm gun, and the diesel engine that provided it with its uncomparable mobility. It was (like all other Soviet vehicles) wideIts outstanding chassis was used in several variants including tank destroyers, flame tanks, and the up-gunned T-34/85. Many claim that this was the vehicle that redefined tank design. It was also most likely the most influential tank used in WWII. Variants are still in use by some poor countries.