On its own, a la Japan in 1904, the Ottoman Empire defeats a major European Power with about the same decisiveness that Japan won the Russo-Japanese War. Ottoman troops must be in possession (but not necessarily annex) some of the territory of the said power (i.e., Ottoman troops in Sicily, the Crimea, Croatia, etc.).
POD must be after 1829, and the victory must take place before 1899.
To me, it seems just about the only posobilities are Italy, AH and Russia.... the others are just t0o far away and powerful
Is it acceptable if the rival is occupying parts of the Ottoman Empire as well? Is a status quo peace accepptable, especially if they aren't the aggresor? Can another state give monetary or diplomatic support?(to the Ottomans)
The Greeks weren't a European "power" in the 19thc, and aren't now, matter of fact.
Could they maybe turn the tables somehow on the Russians in the Russo Turkic 1870's thingie? I dunno, might be close to ASB, or maybe not, strange things do happen in wars sometimes.
Reason I bring it up is that 1. Its a considerable power 2. Didn't everybody kick Russia's butt in the 19thc one time or another?
3. It would make a substantial difference, to the Turks and everyone else
Depends how you define a victory. Regaining even de-jure control over both Romanias is imposible without a major POD, or heavy intervention by another state. But even their de jure influence in Romania was limited.... perhaps they regain Wallachia, and Moldavia becomes a demiltarised neutral buffer? Combined with some minor territorial gains in the Caucasus, this may well be an improvement for the Ottomans on the European stage.
I think that would fufill the terms put forth by FenkMaster.
Japan only won because of the Russian revolution in 1905, which is also what the Ottomans need if they want to defeat Russia on their own in the 19th century.
The Russian population became discontent with the 1877-78 war rather quicky OTL, and they were clearly winning, so if Russia does rather worse then they did OTL, suferring some reverses, and the war drags on a year or 2 longer, you
might see some significant revolution...indeed it would need less then this to set off a revolution in Poland.
Perhaps if the Ottoman treatment of rebels is less harsh, but the the Russians declare war anyway, we could see some form of support from Britain, coupled with a few less blunders by the Ottomans and a few more by the Russians...
As for Italy, might an earlier war over north Africa or ottoman suport for Naples be a pretext? The combine Napolitan/Ottoman navy would significantly larger then Italy's.
AH....maybe not so likely after all(Germany or Russia), unless they initiae the war. Even then Russia will probaly suport them, so the Ottomjan position seems pretty hopeless