Origins
The Ottoman Empire began as a small Anatolian principality founded around 1299 by Osman I, a Turkish frontier chieftain from whom the dynasty took its name (Osmanli, anglicised as Ottoman). Osman’s small state expanded steadily through the 14th century at the expense of the declining Byzantine Empire and the various neighbouring Turkish beyliks.
The decisive expansion came under Murad I (1362–1389), who conquered most of the Balkans and made Adrianople (modern Edirne) the imperial capital in 1369. The 1389 Battle of Kosovo against a Serbian-led coalition effectively secured Ottoman dominance over the southern Balkans, although Murad was killed during the battle.
Constantinople, 1453
The defining Ottoman achievement of the 15th century was the conquest of Constantinople. Sultan Mehmed II besieged the city for fifty-three days and captured it on 29 May 1453. The fall of Constantinople ended the thousand-year Byzantine Roman Empire and made the Ottoman state the dominant power of the eastern Mediterranean. The Hagia Sophia, the great 6th-century cathedral, was converted into a mosque; it would remain so until the Turkish Republic converted it into a museum in 1935 (and back into a mosque in 2020).
Mehmed II made Constantinople the imperial capital under its Turkish name Istanbul (a corruption of the Greek eis tēn polin, “to the city”). The city was rebuilt and repopulated with substantial Muslim, Jewish, and Christian populations.
Imperial peak, 1453–1683
Over the following two centuries the Ottomans expanded across the eastern Mediterranean, the Balkans, the Black Sea coast, the Caucasus, and the Arabian peninsula. Sultan Selim I (1512–1520) conquered Syria, Egypt, and the Hejaz, bringing Mecca and Medina under Ottoman control and giving the Sultan the title of Caliph. Sultan Suleiman the Magnificent (1520–1566) — the longest-reigning and most accomplished sultan — captured Belgrade (1521), defeated the Hungarians at Mohács (1526), expelled the Knights Hospitaller from Rhodes (1522), and besieged Vienna (1529).
The empire reached its greatest territorial extent in the late 17th century, stretching from the gates of Vienna to Yemen and from western Algeria to the Persian Gulf. The siege of Vienna in 1683 — repulsed by a combined Polish, Austrian, and German army under King Jan III Sobieski — marked the high-water mark of Ottoman expansion. The empire would slowly contract from this point until its dissolution.
Government and society
The Ottoman state combined Islamic law (sharia) with imperial decree (kanun). Non-Muslim populations were organised into self-governing religious communities (the millet system) under Ottoman political sovereignty, allowing substantial cultural and religious autonomy. The empire was administered by a sophisticated bureaucracy of Muslim officials, many of them drawn from the devshirme system — the controversial practice of taking Christian boys from the Balkans, converting them to Islam, and training them for imperial service. The Janissary corps, originally formed from devshirme recruits, was for several centuries the most professional standing infantry in Europe.
The long decline, 1683–1922
The empire contracted slowly over the following two and a half centuries under successive wars with the Habsburg Empire, the Russian Empire, and Persia. The European territories of the empire were lost in stages — Greece (1832), Serbia (1878), Bulgaria (1908), most of the remaining Balkan territories (1912–1913). Egypt became effectively autonomous under Muhammad Ali in the 1830s and was occupied by Britain in 1882. The 19th-century Tanzimat reforms attempted to modernise the imperial administration but did not arrest the decline.
The Ottoman Empire entered World War I on the side of the Central Powers in October 1914. The war was catastrophic for the empire: the Arab provinces were lost, Constantinople was occupied by Allied forces in 1918, and the empire’s Anatolian heartland was partially occupied. The Turkish nationalist movement under Mustafa Kemal (later Atatürk) defeated the occupying Greek army in the Turkish War of Independence (1919–1923), abolished the Sultanate on 1 November 1922, and proclaimed the Republic of Turkey on 29 October 1923.
The Ottoman Caliphate was abolished by the new Republic on 3 March 1924, ending one of the longest political institutions in world history.