Osman I and the rise of the Ottoman beylik

Almost nothing about Osman can be stated with certainty. No written source survives from his reign, and the Ottomans began to record his life only in the 15th century, more than a hundred years after his death, so that historians find it hard to separate fact from legend — Colin Imber called the period a “black hole”. According to Ottoman tradition, his father Ertuğrul had been granted the frontier town of Söğüt by the Seljuk sultan, and Osman succeeded him around 1280; later writers told of a dream at the house of the sheikh Edebali that foretold the greatness of his line, and traced the dynasty to the Kayı branch of the Oghuz Turks — a genealogy that many scholars regard as a later invention meant to strengthen its legitimacy. Osman’s principality was one of the beyliks that arose as the Seljuk Sultanate of Rum weakened under Mongol overlordship after Köse Dağ, and its position on the border of the weakened Byzantine Empire gave it ample scope for raids.

The first datable event of Osman’s career is the battle of Bapheus near Nicomedia, where on 27 July 1302 a Turkish force of some 5,000 light cavalry under Osman defeated about 2,000 Byzantine troops sent by Emperor Andronikos II. This is the date accepted by most modern historians (Colin Imber gives 1301 or 1302); older writers such as Edward Gibbon placed the battle in 1299. The Byzantines lost control of the Bithynian countryside, and their towns, isolated, fell one by one. The siege of Bursa (Prusa), conducted from about 1317 by the Ottomans, who lacked experience and adequate siege equipment and had never taken a city of that size, ended on 6 April 1326, when the starving city surrendered to Orhan.

Modern scholars put Osman’s death in 1323 or 1324; Ottoman tradition has him die just before or soon after the fall of Bursa, where he was buried. Under Orhan the beylik took Nicaea (1331) and Nicomedia (1337), absorbed the neighbouring beylik of Karasi and from the 1350s began to establish itself in Europe. The dynasty that took its name from Osman ruled until 1922.