With respect, is this a serious query or a political statement? And if the former, the counter-factual ("what if") format is at the end of the day a fairly pointless endeavor. That does not in any way minimize the import of US participation in the Great War. There are enough primary source materials from Allied combatants expressing the jolt of vigor given their cause and efforts by the introduction of masses of American forces. Of course the US played a vital role in bringing the conflict to an Allied victory. But the millions of dead and crippled Frenchmen, British, Canadians, Australians, Belgians, Russians, Italians, Serbs, etc. helped a bit too, I would suggest.
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