Stalin was hell-bent to make Hitler regret betraying him, throwing everything he had at Germany. The fighting between Germany and the USSR could have been a whole war unto itself. D-Day, and all other major battles involving allied powers, severely weakened Hitlers grasp on Europe, but their main contribution to the war was forcing Nazi Germany to fight a two-front war, which they didn't have the resources or manpower to do.
I'd say 60% of the war was won due to the Russian offensive into Germany, the remaining 40% was due to combined Allied efforts.
I'd say 60% of the war was won due to the Russian offensive into Germany, the remaining 40% was due to combined Allied efforts.