Osman was succeeded by his son Orhan in about 1324 and, following long sieges, he took the important cities of Bursa (1326) and Nicaea (1331).
Following the loss of Nicaea in 1331, Byzantine emperor Andronikos III Palaiologos proposed the payment of tribute to Orhan.
Andronikos needed a free hand in the Balkans where Albania, Serbia and Bulgaria were in revolt against Byzantine rule.
[2] The fall of Nicomedia enabled Orhan to overrun Bithynia and extend Ottoman rule to the eastern shore of the Bosporus.
Apart from the city of Philadelphia, which fell to the Ottomans in 1390, the fall of Nicomedia marked the end of Byzantine rule in Asia Minor.