This seems to be an overlooked POD, but one with potentially significant consequences in Europe and the Middle East given the players involved. Basically, after the Fall of Acre in 1291, there was still a great deal of people who wanted a new crusade. I suppose this was an idealistic thing in Europe, given the tensions in the Mediterranean world at the time (i.e. Angevins vs Aragonese), but it was certainly a thing hence the number of plans for crusades proposed to various kings and the Pope. But it was certainly a possibility--at the end of 1299, the Ilkhanate invaded Syria and destroyed a large Mamluk army at Homs. Cilician Armenia's king Hethum II, an ally of the Crusaders and vassal of the Ilkhanate, sent troops to aid his overlord's campaign. This great victory convinced the Kingdom of Cyprus as well as the Knights Templar and Knights Hospitaller to send a fleet to attack. This fleet only seized the island of Ruad off Syria, occupied Tortosa for several weeks and raided coastal cities from Egypt to Syria while in 1300 the Mongols raided as far as the outskirts of Jerusalem and Gaza. There was also a contemporary anti-Mamluk uprising of Druze, Alawite, and Maronites in the Lebanon region which aided the Ilkhanate.
Wild rumours of fabulous success spread in Rome and beyond, where thousands of pilgrims gathered due to the Pope declaring 1300 a Jubilee year. However, because of fear of an imminent invasion by the Chaghatai Khanate, the Ilkhanate withdrew all their troops from Syria by late 1300 and only sporadically made incursions in 1301 and 1302. The military orders lost Ruad in 1302 due to a Mamluk counterattack (thanks to lack of Mongol presence) and in 1303 the Ilkhanate was crushed at the Battle of Marj al-Saffar near Damascus and they would not make any serious incursions in the future. The Knights Templar themselves were destroyed several years later due to the ambitions of Philip IV of France, and the Knights Hospitaller ignored the "Crusade of the Poor" in 1309 due to not needing a disorderly mob of fanatics for their goal that year (conquering Rhodes from the Byzantines).
It seems to me that had the Ilkhanate only sent a token force to deter the Chaghatai (or asked their allies, the Yuan, to commit more men against them and believed wealth and ransom taken from the Mamluks would make up for the issue with the Chaghatai), then Syria would be occupied with its foremost citadels (i.e. Damascus) besieged and the Crusaders content their flank is secure. It also ensures that come 1301-1303, the Ilkhanate is actually besieging Jerusalem and dictates the Mamluks must focus their efforts there due to the threat to Egypt and not against the Crusaders. These Crusaders might be even greater in number due to the rumours of grand success.
So what happens next to everyone involved? New life has just been breathed into the crusader ideal as a semblance of the Crusader states has been re-established, the Ilkhanate just gained a bunch of land, and the Templars aren't just sitting around idly lending money. What sort of reaction does this get in Europe and the Middle East?
Wild rumours of fabulous success spread in Rome and beyond, where thousands of pilgrims gathered due to the Pope declaring 1300 a Jubilee year. However, because of fear of an imminent invasion by the Chaghatai Khanate, the Ilkhanate withdrew all their troops from Syria by late 1300 and only sporadically made incursions in 1301 and 1302. The military orders lost Ruad in 1302 due to a Mamluk counterattack (thanks to lack of Mongol presence) and in 1303 the Ilkhanate was crushed at the Battle of Marj al-Saffar near Damascus and they would not make any serious incursions in the future. The Knights Templar themselves were destroyed several years later due to the ambitions of Philip IV of France, and the Knights Hospitaller ignored the "Crusade of the Poor" in 1309 due to not needing a disorderly mob of fanatics for their goal that year (conquering Rhodes from the Byzantines).
It seems to me that had the Ilkhanate only sent a token force to deter the Chaghatai (or asked their allies, the Yuan, to commit more men against them and believed wealth and ransom taken from the Mamluks would make up for the issue with the Chaghatai), then Syria would be occupied with its foremost citadels (i.e. Damascus) besieged and the Crusaders content their flank is secure. It also ensures that come 1301-1303, the Ilkhanate is actually besieging Jerusalem and dictates the Mamluks must focus their efforts there due to the threat to Egypt and not against the Crusaders. These Crusaders might be even greater in number due to the rumours of grand success.
So what happens next to everyone involved? New life has just been breathed into the crusader ideal as a semblance of the Crusader states has been re-established, the Ilkhanate just gained a bunch of land, and the Templars aren't just sitting around idly lending money. What sort of reaction does this get in Europe and the Middle East?