The Soviet Union played the most decisive role in the defeat of Nazi Germany in WW2

"LaughingRiddle, we meet again."Pleasure again my good Russian adversary. "I believe that the USSR was the deciding factor, because if Hitler would have chosen to not invade the USSR, then the Allies may not have had the USSR's support." This is possibly true. However, one of the main reasons for the USSR signing the Ribbentropp-Molotov agreement was because Stalin wished to postpone a war with Germany. Indicating the USSR was gearing up for war one way or another before Hitler ever invaded.It is hard to imagine that Stalin, being paranoid, and a little fearful of Hitler/Germany would have not favored the Allies over a much bigger direct threat like Germany. When, and whether or not the USSR would have declared war on Germany had things been different would be be sheer speculation. This would have meant destruction for most, if not all, of the Allies. Hitler invaded the USSR on June 22 1941. By this time, Russia has played neutral in first 1 year and 9 months of WWII in Europe. The allied countries of Denmark, Belgium, Netherlands, France, Poland, and Norway had already been lost to Germany. Germany's attempt to defeat the last major allied resistance in Europe in 1940 came during the battle of Britain in the fall of 1940. Long before Russia entered the war, Germany had failed to secure the military conditions for a successful invasion of the UK and abandoned the notion. Even had Germany not declared war on Russia the next year, there is no strong evidence that the UK would have been defeated. The Royal Navy had supreme control of the atlantic and english channel, and the Luftwaffe had failed to defeat the royal air force. More than that, the Luftwaffe suffered severe losses that would be felt for the the rest of the war. It would seem that Russia not joining the war didn't mean the loss of anymore allies because by the time Russia joined all of the allies within Germany's reach were ALREADY lost...http://en.wikipedia.org...The turning point of the the war is considered to be the Battle of Moscow (which was already taking place during October of 1941, however the United States engaged in the war only in December).When the US joined the war is somewhat irrelevant since the US was providing supplies to Russia long before it entered the war. However, the US did provide valuable military contributions to the war effort. The US kicked germany out of N Africa and knocked Italy out of the war. Americans bombing campaigns would cripple the german war effort as well. Many historians also consider the battles of Stalingrad and Kursk to be the decisive battles and turning points of the war. There is valid arguments for all 3 battles, the battle of Moscow marked the farthest German advance on the Russian capital, but the Germans would generally win victories for many more months in 1942. The german army was very far from defeated after the battle of Moscow, in fact the battle ended not because of German defeat, but because at the end of October the legendary cold of the Russian winter froze the battlefield and the german offensive. Stalingrad was the first decisive defeat to the German army, and marks their furthest advance east before the soviets turned the tide. Kursk marks the crippling of the German army, and the initiative turns decisively to the SOviet for the remainder of the war. Although I do agree that without the support of the Allies, it would have been much more difficult and losses would be greater, but the German war machine was already running out of fuel by the time they reached Moscow.In 1941 German had not exhausted its fuel reserves, instead the German supply line had failed to keep up with the rapid advance and demand of the Front lines. Part of this was due to wether conditions, very muddy terrain, and the fact germany did not enjoy nearly so many motorized supply vehicles unlike the soviets who were provided 400,000 such vehicles by the US. Even the UK's participation in the war was in many ways dependent on US aid. So without such aid it could have been russia completely alone against Germany, italy, and possibly even Japan. Ultimate Victory without RussiaThis topic reasons the possibility of a victory without the eastern front in WWII. It is ostly conjectures, but allows people to maybe get an idea of WWII without russia. One thing that is certain, is that the russian lives scarified to defeat Germany would have had to be be sustained by a different country. THe most likely candidate is the US. However, since WWII ultimately turned out to be a long war of attrition where industrial power became important and the US had such an advantage it is not impossible that the US could have won the war, as it had both the prerequisite manpower and industrial capacity. The main difficulty the US would face is the need for an amphibious invasion of a one front German occupied Europe. This is, however, possible provided the UK remained free. The US strategy would have ended the war in 2 ways, both would mean a much longer WWII. 1. The US will focus on air superiority and industrial bombing of Germany from the UK. The US will push in the peripheries of Germany, such as N. Africa, Italy, Balkans, and Scandinavia in order to exhaust and strangle Germany. Germany itself would not be assaulted until it was surrounded, like Japan. 2. War would continue until the invention of the atomic bomb. Most sources show Germany did not place a particularly high importance on atomic weapons research, unlike the US and UK. It is very likely the western allies would have beaten germany to the bomb, and won the war. To list the possibilities, victory is either not possible without russia (as it might have been impossible to russia to win without the allies) but without Russia the west, particularly the US, would have been guaranteed to suffer a much much higher % of casualties. Victory is very Possible There exist facts that make the possibly of a western allied victory without the USSR very persuasive. A total of 2,124,352 of Germany's 3,904,103 military causalties were sustained in the Eastern front accoridng to wikipedia.http://en.wikipedia.org...This means that 45%, almost half of Germany's losses, were inflicted by non-russian forces. Which raises the real possibility of a victory without the USSR. The US had the industry and manpower to win such a war. And arguably a more effective strategy. US industry was beyond German reach entirely, while the US and UK were able bomb the German industrial heartland. Most of the Russian industrial heartland was lost to German in 1941, which made allied material support to Russia even more important. Maybe Russia could have won the war, but it is hard to see how they could have turned the tide without allied aid and the main industrial area of Russia lost to Germany. While the US is safe and out of reach of Germany Russia has to bear the brunt of a german blitzkrieg. Arguably, the germans would much rather fight an enemy like Russia rather than an enemy they can't reach like the US. And they did end up choosing this.