Michael Peck
One of the most momentous decisions in history was Adolf Hitler's invasion of the Soviet Union on June 22, 1941.
Operation Barbarossa transformed Nazi Germany's war from a one-front struggle, against a weakened Britain and a still-neutral United States, into a two-front conflict. The Eastern Front absorbed as much as three-quarters of the German army and inflicted two-thirds of German casualties.So what would have happened if Hitler had not invaded Russia? The dynamics of the Third Reich and Hitler meant that Germany would not remain passive. In fact, it is hard to imagine Nazi Germany and the Soviet Union not at war, though the question is when this would have happened.
One possibility was invading Britain in 1941, and thus either ending the European war or freeing the up the Third Reich to fight a later one-front war in the East. Thus Operation Sealion, the proposed 1940 amphibious assault on southern England, would merely have been postponed a year. The problem is that the Kreigsmarine—the German navy—would still have been badly outnumbered by the Royal Navy, even with the addition of the new battleship Bismarck. The British would have enjoyed an additional year to reinforce the Royal Air Force and to rebuild the divisions battered during the Fall of France. Britain would also have been receiving Lend-Lease from the United States, which by September 1941 was almost a belligerent power that escorted convoys in the North Atlantic. A few months later, America did formally enter the conflict; despite the Japanese advance in the Pacific, the United States would certainly have concentrated its growing strength on keeping Britain unconquered and in the war.
http://nationalinterest.org/feature/what-if-hitler-never-invaded-russia-during-world-war-ii-17492
