Dementor
Interesting. I would understand the allies trying to get Serbia to make concessions and it refusing. Never heard of Greece making an offer and given the division in Greece between PM and king not sure how that would have worked. Do you know when this was?
I was thinking that a slightly more successful Gallipoli coupled with a big diplomatic push form Bulgaria, because they realise they need it's army to secure victory in Thrace. Both offering them the province, plus extensive military and economic aid plus possibly a subtle hint that if Bulgaria pushed the issue against an exhausted Serbia after the war the allies would give implicit support or at least not oppose them. Something I've played around with for a TL that sees WWI go different. Basically getting Bulgaria on the allied side there and then would be decisive in ensuring [barring extreme incompetence by the allies] an allied victory.
Steve
The story that I've heard was that apparently that the Greeks offered some territory - in Eastern Thrace, apparently. The Bulgarian prime minister was willing to consider it, but the army generals rejected it out of hand. On second thought, the whole story seems rather dubious. I haven't found any confirmation by reliable sources (and forums are not reliable sources
). Also, Bulgaria had a semi secret alliance with Turkey during the war and even sent armed bands across the border. So the story is quite likely to be just a story. Sorry if I've mislead you.
As for intervening in 1915, that's plausible. But apart from the dubious gains, and the weak position of the Entente at this point, the German effort was far more sustained - they actually persuaded the Ottoman Empire to cede some territory to Bulgaria. Also, the Bulgarian king and prime minister had a good personal relationships with the German government, including a pension they were to receive regardless of the outcome of the war.
So you're correct that a more successful initial Gallipoli would be a crucial requirement.
If the Bulgarians managed to win the Second Balkan War, that might be doable.
I would say that Bulgaria winning the Second Bulgarian war under conditions similar to OTL is almost ASB. Defeating the Greek and Serb armies is possible (even in OTL the war was verging towards a stalemate) but what would the point of that if Romania and the Ottoman Empire overrun the rest of the country? And stopping them from intervening would require the intervention of most of the Great Powers, which was not likely in this time period.
This is probably the third most discussed topics of alternate history in Bulgaria and the general consensus is that Bulgaria would have to demobilize and try to gain the favor of the Great Powers - not exactly the actions of a Prussia of the Balkans
Check out A Shift In Priorities it has a Central Powers victory. Which makes a stronger Bulgaria.
https://www.alternatehistory.com/discussion/showthread.php?t=111014
It's rare (and unpleasant) time line where Bulgaria is a ruthless mini-empire.