As far as ending World War One.
Since the issue was raised that the United States intervention in 1917 was what ended the war.
Silly on the face of it and sillier still the further you delve into the idea.
Britain and the rest of the Triple Entente (although there were far more than three of them) had the propaganda going about “That Small nations might have the same rights as the Great Powers”.
Just not nations like Ireland, India, China, Kenya, VietNam (only “our” French allies were calling it “Cochin China”… Cochin is French for “pig”) the Congo, the Sudan, South Africa… you know, the Small Nations inhabited by those the European Royalists considered “inferior”.
So while the Band of Cousins, related by blood and by their arrogance, sent “their” subjects to do bayonet charges against poison gas and belt-fed water-cooled machine guns, eventually, the worst of the lot, Cousin Nicholas Romanoff, pissed off his Peasant Slaves errr Lawfully Appointed Subjects to the point that they got sick of it, and gave him and his Demon Spawn family exactly what they deserved..
If it had spread much further, and the American intervention was the only thing the “free” nations had to end it…(Free to Obey Your King as though he were anointed by God) (and the Royalists still believe that they ACTUALLY ARE anointed by God)
If there were no American intervention the general mutiny that was building in ALL the trenches, French, Belgian, English, Turkish, German, Austrian… the same way it had amongst the Russian Conscripts, would have reached it’s natural apex, and they would have gotten rid of THEIR parasite class the same way the Russian people had.
The war would have ended a lot sooner, and even the Spanish Influenza epidemic might have been averted.
And since it wouldn’t have ended on terms imposed by the “victors”… it would actually have been over.
Instead of, you know, our generation still fighting the same war, different battles.