Well better weather puts it outside the scope of this forum, also this assumes that you buy the claim that it was the Balkans that somehow delayed Barbarossa and not German logistics and also that it was the weather that derailed Barbarossa all by itself, rather than the Wehrmacht reaching the maximum range their supply system could support while having underestimated the strength of the Red Army by a factor of three or four.
The big problem with invading the USSR is logistics. As you move further and further east, you have to tote men and materials further and further over land using more and more fuel and vehicles. One way to mitigate this is sea based transport. If Turkey joins the Axis, then they can let Italian navy units into the Black Sea and the Axis can dominate the Black Sea. This creates the opportunity to ship things long distances by water less expensively and faster (and with less potential for partisan interference) than by land. This creates the potential for actually taking the Caucasus region and depriving the USSR of the Baku oil. So the Turkey issue is an important one.
As it was, the US won WW2. Its casualties were light and it ended the war significantly stronger than when it began. But Japan that:
Is it true that weather is outside the scope of this forum? I don't see anything about it in the rules but I am not enough of a regular to be confident that I am not missing something.
Look up Japan's TFR in the 1930s, it's close to 5. With a TFR in that ballpark, and the expectation that it'll probably increase if you're victorious, you can plan to do what I'll call 'replacement style ethnic cleansing'---as in, you come in and displace mostly by demographic means the existing population. This is close to the US model of ethnic cleansing. If you haven't got that level of TFR, you're stuck with over the top Nazi Generalplan-style ethnic cleansing, where you basically have to kill most of the population that you're going to ethnically cleanse. If you've got an even higher TFR, you can ethnically cleanse without even having an actual plan for doing so (some would argue that's the true US model in the 1800s).
FDR was not going to negotiate a peace deal other than unconditional surrender. He was very clear on this, and he also greenlit the Manhattan Project so yes, I would say getting the western allies to agree to that would require a different US President.
As has been discussed in other threads and by other knowledgeable users no one can say for certain what FDR would have definitely done if the USSR was knocked out and the war continued as the prospect of millions of casualties loomed over the WAllied leadership. You can make an argument either way and both outcomes are plausible. They were human beings, not cold blooded robots in shining armor intent on slaying the evil dragon no matter what like something out of a comic book.
I think its outside the bounds for post-1900 but I stand to be corrected and in this case I don't it actually had as much of an impact as some liked to claim after the war.
Merely making an argument doesn't make something plausible. Even with the USSR knocked out, the Nazis would still be facing supply shortages as the infrastructure to extract and transport the resources of eastern Europe would be destroyed and the western allies would still blockade Nazi-occupied Europe and prevail in North Africa. Then the Nazis would face the issue of actually garrisoning their conquests while facing attacks by partisans. There's the fact that you can't heavily fortify the entire coast. There's the issue of nukes and firebombs. British intelligence and American production far exceeded their German counterparts. There is no indication that the carnage made America consider peace talks, and Britain would only do so over Churchill's dead body. We do have FDR going on record (to thunderous applause) saying that the American people would fight to "absolute victory." At the Casablanca Conference FDR insisted on unconditional surrender. There is no evidence that he would cry uncle and much to the contrary.
Exactly. If the USA gets involved, even "only" economically, then axis can't win.
Divine intervention to save the Nazis... would make for a good short story. If Hitler was wildly popular after the Fall of France, he'd probably be deified if that happened.
