By the accession of Andronicus in 1328, the Imperial territories in Anatolia had dramatically shrunk from almost all of the west of modern Turkey. Andronicus decided to relieve the important besieged cities of Nicomedia and Nicaea, and hoped to restore the frontier to a stable position.

The Byzantine Emperor Andronicus III gathered together a mercenary army and set off towards Anatolia on the peninsular lands of Kocaeli. But at the present towns of Darica, at a site then called Pelekanon, not too far from Üsküdar, he met with Orhan's troops. In the ensuing battle of Pelekanon, the Byzantine forces were routed by Orhan's disciplined troops. Thereafter Andronicus abandoned the idea of getting the Kocaeli lands back and never again conducted a field battle against the Ottoman forces.