The dynasty that grew from a small Anatolian frontier principality into the empire that conquered Byzantine Constantinople in 1453.
The dynasty takes its name from Osman I, a Turkish frontier chief in north-western Anatolia around 1299 whose small principality bordered the weakened Byzantine Empire. Ottoman tradition, recorded much later, wraps his rise in the dream of a great tree growing from his body — a legend of destiny rather than documented fact.
Osman’s followers were ghazis, frontier warriors drawn by plunder, land, and faith to raid Byzantine territory. What made the Ottomans outgrow their neighbours was their position on the richest frontier and their early crossing into Europe.
Orhan took the Byzantine city of Bursa in 1326 and made it a capital, and by 1354 the Ottomans held Gallipoli, their first foothold in Europe. Murad I drove deep into the Balkans, taking Adrianople (Edirne) and defeating a Serbian-led coalition at the Battle of Kosovo in 1389, where he was killed in the moment of victory.
His son Bayezid I "the Thunderbolt" pressed on, annihilating a western crusade at the Battle of Nicopolis in 1396 and blockading Constantinople itself.
In 1402 the conqueror Timur invaded Anatolia and destroyed Bayezid’s army at Ankara, taking the sultan prisoner. The Ottoman state fragmented in a civil war between Bayezid’s sons — the Ottoman Interregnum of 1402–1413 — that nearly ended the dynasty.
Mehmed I emerged as sole ruler in 1413 and painstakingly reunited the realm. His son Murad II beat back Hungarian and Polish crusaders at the Battle of Varna in 1444, restoring Ottoman dominance in the Balkans.
Mehmed II came to the throne determined to take the Byzantine capital. In 1453, with huge cannon, a fleet dragged overland into the Golden Horn, and a relentless siege, he stormed Constantinople, ending the thousand-year Byzantine Empire and making the city — Istanbul — his imperial capital.
The Fall of Constantinople turned the Ottoman sultanate into a world empire and earned Mehmed the title "the Conqueror". Under him and his son Bayezid II the state was given the institutions, law, and administration of a great power.
Within a century and a half the House of Osman had risen from a frontier beylik to the master of south-eastern Europe and the Near East. Its early sultans built the devshirme, the Janissary corps, and a centralised military-administrative system that would carry the dynasty for centuries beyond the medieval period.
By 1453 the Ottomans had replaced Byzantium as the dominant power of the eastern Mediterranean, reshaping the political and religious map of Europe and the Islamic world.