Great, you watched that show on Netflix about Stalin and how his stupidity almost lost the war. Nobody is disputing that, even in Russia. But to claim that D-day somehow magically won the war for UK/US is bogus. Nazis surrended in Stalingrad in February of 1943. Battle of Kursk took place in August 1943. By the time Allies landed in Normandy the Soviets were pushing west through Ukraine, Belarus and Poland.