A frontier beginning
The Ottoman state started as one of several small Turkish principalities, called beyliks, in western Anatolia around the year 1300. The region had been dominated by the Seljuk Sultanate of Rum, but its power collapsed after a heavy defeat by the Mongols at Köse Dağ in 1243, and it was reduced to dependence on the Ilkhanid Mongols. The wider upheaval of the Mongol conquests left a power vacuum in Anatolia, and many local leaders competed for land and followers there, along the frontier with the weakened Byzantine Empire.
The dynasty is named after Osman, whose dates are uncertain; he is usually placed as the leader of a small band from about 1299 or 1300. Very little contemporary writing about him survives, and the stories told of him, such as a famous dream of a tree growing from his body, were written down a century or more later. What can be said is that his group was based near Byzantine Bithynia and that it won a victory over a Byzantine force at Bapheon in 1302. This success drew warriors to his cause.
Early growth under Orhan and Murad I
Osman’s son Orhan took the important city of Bursa in 1326 after a long siege, and it became the first real Ottoman capital. Nicaea fell in 1331 and Nicomedia in 1337. The Ottomans then took advantage of divisions inside the Byzantine Empire. Byzantine contenders hired Ottoman troops during their civil wars, which gave the Ottomans knowledge of the Balkans, and in about 1354 they established themselves at Gallipoli on the European side of the Dardanelles, after an earthquake damaged its defences. From this base they expanded into Thrace.
Orhan’s successor Murad I (reigned c. 1362 to 1389) took Adrianople, known in Turkish as Edirne, in the 1360s, and it became the new capital; scholars debate the exact year. His forces defeated Balkan rivals, and they pressed Serbia and Bulgaria into vassalage. Murad was killed at the battle of Kosovo in 1389, although the Ottomans retained control of the field and Serbia became a vassal. These conquests gave the dynasty a growing European province and a stream of resources and soldiers.
The army and the state
Several features made this expansion possible. Early Ottoman forces included mounted warriors on the frontier, supported by those motivated by religion, by plunder and by the prospect of land. Over time the rulers built a more centralised system. One method was the recruitment of Christian boys from the Balkans through the devshirme, who were converted, educated and trained for service as soldiers or officials. The best known units were the janissaries, an infantry corps armed increasingly with firearms. Another method was the timar system, in which cavalrymen received the income from land in return for military service. Historians continue to debate the date and extent of the devshirme, but it was well established by the fifteenth century.
The Ottomans also relied on practical tolerance of conquered populations. Christian and Jewish communities were allowed to keep their religious institutions under their own leaders in exchange for taxes, an arrangement later described as the millet system, although historians stress that this tidy term was developed later and that practice varied from place to place.
Bayezid, Timur and recovery
Murad’s son Bayezid I, nicknamed Yildirim, the Thunderbolt, defeated a European crusading army at Nicopolis in 1396, and he built up pressure on Constantinople. But his expansion in Anatolia brought him into conflict with Timur, the Central Asian conqueror whose realm gave rise to the Timurid empire. At the battle of Ankara in 1402, Timur crushed the Ottoman army and captured Bayezid, who died in captivity in 1403.
The result was an interregnum of roughly a decade in which Bayezid’s sons fought one another. Mehmed I eventually reunited the realm in 1413. The episode showed that the Ottoman state, though impressive, was not unbreakable, and it also shows how Ottoman fortunes were tied to events in the wider Islamic and Mongol-influenced world. Under Murad II (reigned 1421 to 1444 and 1446 to 1451) the Ottomans recovered, defeated a crusading force at Varna in 1444, and prepared the ground for the great conquest.
1453: the conquest of Constantinople
Mehmed II came to the throne for a second time in 1451, at about the age of nineteen. His goal was Constantinople, the capital of the Byzantine Empire, which in the fifteenth century was a much-reduced state, holding little more than the city and a few surrounding areas. The city’s mighty land walls had resisted many attackers, and the Byzantines are the last continuation of the Roman state that survived long after the fall of Rome in the west.
The siege began in April 1453. Mehmed’s army was supplied with very large cannon, including pieces built by the engineer Orban, and the Ottomans also used traditional siege engines and mining. A chain across the Golden Horn kept the Ottoman fleet out of the harbour until ships were moved overland, according to the traditional account. The defenders under Emperor Constantine XI were far fewer in number, helped by a contingent of Genoese and Venetian volunteers. After about seven weeks, on 29 May 1453, the city fell, and Constantine died in the fighting. The Hagia Sophia was converted into a mosque, and Constantinople, soon known as Istanbul, became the Ottoman capital.
A multi-continent empire
The conquest was a turning point, but expansion continued. Mehmed II added Serbia, much of Greece, Bosnia and the Black Sea coast, including Trebizond in 1461. Later, Selim I (reigned 1512 to 1520), a great-grandson of Mehmed II, defeated the Safavids of Iran at Chaldiran in 1514 and then the Mamluk Sultanate in 1516 to 1517, bringing Syria, Egypt and the holy cities of Mecca and Medina into the empire. Under Suleiman I (reigned 1520 to 1566) the Ottomans took Belgrade in 1521, Rhodes in 1522 and won at Mohacs in 1526, which led to the Ottoman domination of much of Hungary. A siege of Vienna in 1529 failed. Baghdad was taken from the Safavids in 1534, and Ottoman naval power, helped by commanders such as Hayreddin Barbarossa, extended to North Africa.
By the mid-sixteenth century, the empire controlled territory in Europe, Asia and Africa, and ruled over a population of Muslims, Christians and Jews. The caliphate had once been the central Islamic institution, and the Abbasid line had earlier been maintained under Mamluk protection in Cairo; the Ottoman sultans did not make the caliphal title central to their rule until much later. Ottoman power continued, with periods of strength and crisis, until after the First World War, a long story that this article only begins.