FDR, Stalin, and Churchill all won that war. History is super messy!

So did Hitler. I mean, he did end up killing Hitler, that's gotta count for something!

Team America to the rescue! But it does seem like without FDR it would have been won for the allies anyway.

I think this kind of counterfactual is pretty impossible to do.

Do you mean that it would have been won without any US involvement? Or do you mean the US involvement would have proceeded similarly with a different president?

From my cursory sense of things it seems like both are probably true. The U.S with FDR obviously contributed to it ending when it did, but so did other countries who were there earlier and sacrificed more. The U.S seems like more of a winner in the sense that they sacrificed relatively little while getting the most out of it, but I don't know if that's a good use of the term "won" in the context of a world war.

*yet

> Stalin didn’t win

...even backed by crucial US supplies

Historical note: Stalin and Hitler agreed to start WW2 by invading Poland in September 1939.

So Stalin may have played a part in ending WW2, but don't forget his part in starting it.