The Turks entered Anatolia at the beginning of the 13th century after migrating westward from Central Asia following the battle in which Muslims defeated the Byzantines in 464 AH (1071 CE). This battle, fought in eastern Turkey, is known as the Battle of Manzikert (Malazgirt), where the Byzantine army was decisively defeated.
Osman Gazi gathered all the tribes around him after becoming the chief of the Kayi tribe in 1281.
At that time, Anatolia was home to the Byzantine Empire, the Empire of Trebizond, the Anatolian Seljuks, Venetian and Genoese colonies, and various Anatolian Turkish beyliks. There was never any political unity in Anatolia, and all these states paid tribute taxes to the Ilkhanid (Mongol) state in Iran.
In the Balkans, the Byzantine Empire coexisted with the Serbian, Bulgarian, Hungarian, and Albanian kingdoms, as well as the principalities of Bosnia, Herzegovina, and Bogdan. Religious and political conflicts were frequent among these states.
Reasons for the Ottomans’ Rapid Rise and Strength
- The Ottomans neighboured the Byzantine Empire, which was experiencing internal instability in its geographical position.
- The Ottoman state did not participate in conflicts between other beyliks.
- The Ottomans adopted a policy of tolerance and justice.
The First Battle of the Ottoman State
The first military campaign in Ottoman history was the “Armenian-Beli Battle” (Ermeni-Beli Savaşı) in 1284. This battle took place in the village of Hamza Bey, about 10 km from İnegöl in Bursa. With this battle, the Ottomans captured their first fortress in 1285 — a turning point in establishing Ottoman control.
The Ottoman-Seljuk Relationship
During this period, the third Seljuk Sultan, Alaeddin Keykubat, granted Osman Gazi control of the Eskişehir and İnönü regions.
While Osman Gazi continued his intensive political and social activities, the Ilkhanids exiled Sultan Alaeddin Keykubat III, leaving the Seljuk state without a sultan.
Bilecik became the first capital of the Ottoman state. The Ottoman state was officially founded in 1299, and Bilecik was chosen as its capital.
Date of the Ottoman State’s Founding
Some sources mention that the founding date of the Ottoman state was 27 July 1301. On that date, Ottoman forces defeated the Byzantine army in the Battle of Bapheus (Bafeus) and secured their independence.
Osman Gazi appointed his brothers over the newly acquired territories.
Staying true to old Turkic traditions, Osman Gazi divided the lands acquired by the state among his brothers, sons, and companions. For example:
- He gave the city of Eskişehir to his brother Gündüz Bey.
- He gave the region of Karacahisar to his son Orhan Gazi.
- He gave the İnegöl region in Bursa to Turgut Alp.
These areas were located on the frontiers of the Ottoman state, which encouraged further expansion of its borders.
In 1302, the Ottomans attacked the Byzantine army in the village of Koyun Hisar in Bursa and emerged victorious. In 1303, the city of İznik was besieged by the Ottoman army, which also captured the fortress of Marmaracık.
At the end of the Dinboz Battle (Dinboz Savaşı) in 1306, the Ottomans seized the fortresses of Kestel, Kete, and Ulubat in Bursa. Following this, the first military treaty in Ottoman history was signed.
