I'm curious though to see how Ioannis VI's pronoia reforms might affect this event. It has been over twenty years he applied the pronoia reform in Gallipoli (July 1331 entry), and we already saw the Byzantines repelling the Genoese assault on Lesvos (May 1347) which the Empire had reconquered back in 1329 and where it had applied the pronoia system early (September 1329, March 1330).
Will Gallipoli fall that easily to the Turks this time?
I would bet that most of the reforms have been diminished after the civil war that destroyed much of Constantinople's state capacity. Thrace has been plunded for years by different mercenary armies of the two sides. I think that now as in OTL, the cities are left to basically fend for themselves. At this point - even before the fall of Gallipoli, the Ottomans are raiding as far as Raidestos.
Having said that, it seems that in 1353-1354, the Ottoman forces in Europe were quite limited. It seems that before the earthquake, Suleyman Pasha had around 3,000 men.
Moreover, Doukas mentions that Suleyman was killed in a battle against Matthew Kantakouzenos in 1357. Even if it was not the case, it indicates that until 1357 the Byzantines had some capacity of resistance,
At the time of his grandfather one may note Gallipoli was retaken by Amadeus of Savoy and held for almost a decade... during that decade the Ottomans expanded in Bulgaria and Macedonia...
Well, by the time of the Savoyard Crusade, the Ottomans had almost a decade of moving whole Turkmen tribes to Thrace, not just warriors. Their families and flocks as well. The Gallipoli peninsula was colonized in 1357-1359 and afterwards the tribes expanded north. By the time of the Savoyard Crusade, the Ottomans controlled basically all Thrace other than Adrianople and Bizye that were blockaded and they had reached the Nestos River. At that point, it was doable to sustain the ottoman state in Europe with some luck: the one time their enemies managed to field a proper army, they were drunk and were slaughtered in their tents by a much smaller ottoman host. If someone in alternatehistory.com wrote the Battle of Marica as Deus ex Machina, people would accuse him of sloppy writing.
But if the Savoyard Campaign took place a decade earlier in 1356? Then I think its impact would have been different.
And it is not as if Theodore would be dense enough to disregard the ottoman threat for years at a time. Even if that was the case, the Despotate's merchants and especially the Monemvasiots that had a great deal of commercial presence in the region, would find the Ottomans controlling both sides of the Dardanelles rather threatening and could covet Gallipoli for themselves. They had a merchant colony in Pegae after all.
And did the Savoyard crusade actually had a permanent naval presence to interdict the Straits? I think the Lascarids, being already established in the region can maintain such long term interdiction unlike the crusaders.
Exactly! The Green Count gave Gallipoli back to Ioannis on his way home. I sincerely doubt that it included all the Gallipoli Peninsula. There are no mentions of rebuilding the 6km-long wall at Plagiarion (Bolayir) and garrisoning it. Constantinople did not have the means to turn the Gallipoli Peninsula into an offensive base to cut off the Ottomans from Asia Minor. Most likely, they kept just the city of Gallipoli with the rest of the peninsula in ottoman hands.
Overall, the ability of the Catepanate (without any help from Sicily) to capture the Gallipoli Peninsula and turn it into a defensive and offensive base, is incredibly more potent than that of Constantinople in 1367.
This was actually tried in real live during the Varna crusade with a crusader fleet blockading the straits. So Murad marched further north to the Bosporus... where he found Genoese ships to transport his army over to Europe.
Acting like that against the Byzantines and acting like that against the Sicilians is a different thing altogether.
Genoa is fed with sicilian grain and its trade in the East can continue only with Syracuse's approval. Venice has an extremely limited window of opportunity to act like that- before 1356 when Lajos focuses towards them - a focus that ended up with the loss of Dalmatia in 1358. After that point, it would be extremely risky to go to war with Sicily. Having said that, it is one thing to transport an army
once and another to facilitate the transport of whole tribes over many years.