With all your brilliant suggestions about what Germany should have offered, you still blind out that the Entente wouldn't negotiate.
The Tsar didn't negotiate either. Neither did Kerenskij. But Lenin did.
I agree that we do not talk about certainties; but about last straws which would have provided a different path of events than the straw the German leadership picked, i.e. the Kaiserschlacht-offensive which squandered German reserves and ressources and whose failure destroyed the morale across the Western Front.
I therefore claim that the POD only makes sense if the negotiations do not only precede the Kaiserschlacht, but have the political effect of giving up the offensive and deliver a flexible defensive (not insisting on every possible counter-attack, but only on the most necessary and promising ones)
German never had offered negotiations which would give up what the average Entente soldier could believe he was fighting for: the liberation (and satisfaction) of Belgium and/or a perspective for Alsace-Lorraine.
Just as no side could hold the Red revolution in Russia secret, such an offer would have an impact if sold correctly (although that would need another POD: an improvement of the abysmal German public relations/propaganda)....and with 1918 not looking like 1914, but like 1915 or 1917.
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Germany cannot offer Austro-Hungarian possessions? Karl was not too shy about offering Alsace-Lorraine. I don't belong to those who claim that the Danube monarchy was only a puppet state by 1918. But if Germany would make a peace-offer which entails possible concessions, then Karl would probably swallow the toad to offer the Trentino (but, as one should note in my enumeration, not Trieste or Istria).
The problem that everyone's eliding over I think is that Germany ended up collapsing, as are the Ottomans and Habsburgs. Sure, Russia's out of the game, but America's ramping up. Time isn't on Germany's side.
I agree. However, sparing Germany the Kaiserschlacht and using some of the squandered troops to stabilize the Italian and Balkan fronts as well as the Ukraine would do some good.
Additionally, I wonder if Turkey collapsing alone would do the Entente much good besides creating an awful quagmire sooner than in OTL.
In the west with Belgium and the French provinces, the answer is also pretty simple - if the Allies want an unconditional hand-over just so that they can use them as offensive bases for war into Germany, then they will have to take them house by house, with the area in rubble by the end of it. If the handover is only after an armistice is in place, then the area would be handed over intact.
I am sure the Belgians would read the offer very carefully.