Ilkhanate campaign to Bithynia

During these wars, Byzantium asked for help from the Ilkhanids and the Ilkhanids sent an army to defeat the Ottoman Beylik. These wars were part of the struggles between Byzantium and the Ottomans. Byzantium asked for help from the Ilkhanids to counter the Ottoman Beylik and the Ilkhanids sent an army to defeat the Ottoman Beylik.

Bithynia Campaign (1308)
Part of the Byzantine–Ottoman wars
Date 1308 Location Bithynia Result Ilkhanid-Byzantine victory Territorial changes Ilkhanids captured Ottoman fortresses in Bithynia
Belligerents
Ilkhanate Byzantine Empire	Ottoman Beylik
Commanders and leaders
Andronikos II Unknown Ilkhanid leader	Osman I
Strength
30.000	Unknown
Casualties and losses
Unknown	Unknown

Campaign

In 1302, Osman I of the Kayi Khanate achieved a decisive victory over the Romans, laying the foundation for the Ottoman Beylik. Three years later, in 1305, Byzantine Emperor Andronikos II sought assistance from Öljaitu, the Ilkhanid ruler, to combat the growing Ottoman threat. In response to the Byzantine emperor's request, Öljaitu pledged to send 40,000 of his troops to aid Byzantium. By 1308, Öljaitu had dispatched 30,000 Ilkhanid soldiers to Bithynia to support the Byzantine forces. This Ilkhanid army succeeded in recapturing several Ottoman-held castles and towns in the region and dealt a blow to Osman I's forces. Despite this temporary setback, however, the Ottoman expansion continued unabated.