Orhan

Orhan captured the city of Bursa from the Byzantine Empire after a prolonged siege. He made Bursa the first Ottoman capital, establishing it as a political and economic center that would serve as the base for further expansion into Europe.

Orhan defeated a Byzantine army led by Emperor Andronikos III at Pelekanon near Nicomedia. This victory secured Ottoman control over northwestern Anatolia and forced the Byzantines to abandon attempts to reclaim lost territory.

Orhan captured the Byzantine city of Nicomedia (modern

Orhan married Theodora, the daughter of Byzantine emperor John VI Kantakouzenos, as part of a political alliance. This marriage strengthened Ottoman-Byzantine relations and gave the Ottomans a foothold in European affairs.

Orhan is traditionally credited with creating the Janissary corps, an elite infantry unit composed of Christian boys taken through the devshirme system. This force became the backbone of the Ottoman military, though its exact origins are debated.