This is a meme that won’t die.
Tracing it’s origins, we might suspect it came out as a sort of Cold War theme to show that the Russians really weren’t so bad even if it wasn’t actually communist propaganda or simply contrarian.
The argument goes something like this: without the eastern front and the huge numbers of casualties the Soviets took, the Germans wouldn’t have been defeated.
I’ve always argued that this is retrospectively false due to the simple fact of the atomic bomb. Even if the Normandy invasion had stalled or failed, the Allies were still capable of bombing Germany. The Allies had air superiority (thanks to American output) for most of the war.
A nuclear bomb dropped on Berlin would have ended the war even if the Soviets were never able to get through Kursk, even if we never got off the beach in Normandy.
Prospectively, this is also true, though I’ve never bothered to put together a cogent argument before. Here goes.
First, the Soviets actually weren’t in the war at first. Britain pretty much stood alone, because the Soviets and the Nazis had struck a bargain, remember? Once the Germans invaded the Soviet Union, they chose to open that second front. They also declared war on America (though the isolationists could have prevailed if earlier on we hadn’t more or less taken sides. I’m glad we did, but it’s not like we were sucked in unwillingly against Germany).
Second, we sent the Soviets lend-lease equipment. Without it, would they have been able to do what they did? Doubtful. The Germans got very close to taking European Russia. The lend-lease equipment was couple with Stalin’s constant demand that we launch a second front in Europe ASAP.
General Marshall almost resigned over FDR going along with the British and delaying that invasion as we did. The Soviets clearly didn’t think that the essential element to victory was their own arms. They knew America’s involvement was essential.
As I touched on, we very well could have stayed out of Europe and attacked the Japanese first. Yes, yes, Germany declared war on us, but that was a formality. We were neutral in name only. Still the choice to prioritize Germany was largely due to the simple fact that everyone knew at the time that Britain and the Soviet Union might not be able to stand alone even with American production to supply them.
The Japanese never stood much of a chance other than by tiring us out in a war of attrition. They simply lacked the manpower and resources to fight a 1940s war against the United States. Germany did not. Germany, if it had captured more oil, might have been able to force a stalemate with most of Europe in its hands.
That is, until the atomic bomb.
In sum, the political and military actors behaved as if the United States was the essential Allied party, the United States produced the materiel necessary for the victory, the United States also won by miles the race to the atomic bomb.