Osman I
Osman I was the founder and sultan of the Ottoman Empire.
History
Osman I was born the son of Ertuğrul, an uch bey (marcher lord) of the Sultanate of Rum. He commanded Söğüt near the border with the Byzantine Empire.
After Ertuğrul's death in 1280, Osman succeeded his titles. He was a militarist and rapidly expanded his beylik into Byzantine lands.
At the same time, Iconium was in crisis. Kaykhusraw II, son of Kayqubad I, had stood against the Ilkhanate but lost. He and his successors continued as vassals and faced frequent intervention. In 1297, the Mongols removed Mesud II from power and installed Kayqubad III. In an attempt to consolidate power, Kayqubad purged the court and state bureaucracy, but this only damaged his own legitimacy. Within a few years the Mongols would intervene again to preserve the peace; Kayqubad would be executed and Mesud re-installed. Mesud's second reign would last only a few years past that and the sultanate is effectively dissolved in 1308.
Kayqubad III granted Osman command over all lands he conquered, an honorary title that placed him just below the sultan himself, an exemption from taxes, and permission to mint coins. Following the sultanate's fall, he declared himself padishah. Several neighboring beyliks threw their support behind Osman, declaring him sultan.
Osman's military conquests continued up to his death in 1323, during the siege of Bursa, which his son and successor Orhan made the new capital.