By the accession of Andronikos in 1328, the Imperial territories in Anatolia had dramatically shrunk from almost all of the west of modern Turkey forty years earlier to a few scattered outposts along the Aegean Sea and a small core province around Nicomedia within about 150 km of the capital city Constantinople.

Andronikos decided to relieve the important besieged cities of Nicomedia and Nicaea, and hoped to restore the frontier to a stable position.

At Pelekanon, a Turkish army led by Orhan I had encamped on the hills to gain a strategic advantage and blocked the road to Nicomedia.

The Ottomans conquered Nicaea in 1331 and Nicomedia in 1337,[6] thus building up a strong base from which they eventually swept away the Byzantine Empire as a whole.

[9] With the capture of these cities and the annexation of the Beylik of Karasi in 1336, the Ottomans had completed their conquest of Bithynia and the north-western corner of Anatolia.