The Ottoman Empire was founded by Turkish tribes in Asia Minor and rose to become one of the most dominant states globally during the 15th and 16th centuries. The empire’s reign lasted over 600 years and concluded in 1922 upon its replacement by the Turkish Republic and several successors across the Middle East and southeastern Europe. At its peak, the Ottoman Empire covered a vast territory, spanning most of Southeastern Europe up to the borders of Vienna, incorporating present-day countries such as Hungary, the Balkans, Greece, and parts of Ukraine.
Moreover, it controlled areas of the Middle East, now occupied by Iraq, Syria, Israel, and Egypt, and extended its influence over North Africa as far as Algeria, as well as larger parts of the Arabian Peninsula. The name ‘Ottoman’ refers to the ruling dynasty, founded by Osman I, a nomadic Turkmen leader who established both the empire and the dynasty around 1300.
The Ottoman State until 1481:
The Age of Expansion
The initial phase of Ottoman history was marked by uninterrupted territorial expansion, during which the Ottoman Empire’s rule extended from a minor northwestern Anatolian principality to encompass the majority of Southeastern Europe and Anatolia. The political, economic, and social institutions of the classical Islamic empires were merged with those inherited from Byzantium and the great Turkish empires of Central Asia. They were then re-established in new forms that have characterized the region into modern times.
This process of amalgamation resulted in the origins and expansion of the Ottoman state during the period of c. 1300-1402.
During their early expansion, the Ottomans led Turkish warriors who fought for the Islamic faith, with the honorific title “ghāzī” (Arabic for “raider”). Their opponents were the declining Christian Byzantine state. The founders of the dynasty, Osman I’s ancestors, belonged to the Kayı tribe and migrated to Anatolia along with a large group of Turkmen Oğuz nomads. The Seljuq dynasty, consisting of nomads who migrated from Central Asia, was established in Iran and Mesopotamia during the mid-eleventh century. They overcame Byzantium after the Battle of Manzikert in 1071 and gained control over eastern and central Anatolia during the twelfth century.
The ghazis engaged in battles against both the Byzantines and the Mongols, who invaded Anatolia following the establishment of the Il-Khanid empire in Iran and Mesopotamia during the latter half of the thirteenth century. Following the collapse of Seljuq authority and its replacement by Mongol domination, which was established through direct military occupation of much of eastern Anatolia, several independent Turkmen principalities came into being in the remaining territory, one of which was headed by Osman.
Osman and Orhan
Orhan was the second ruler of the Ottoman dynasty, reigning from 1324 to 1360.
After the final Mongol defeat of the Seljuqs in 1293, Osman became the prince (bey) of the border principality that occupied Byzantine Bithynia in northwestern Anatolia near Bursa. He led the ghazis in battles against the Byzantine army in that region. Osman and his successors faced pressure from the dominant Turkmen principality of Germiyan to the east. As a result, they targeted Byzantine territories lying along the Bosporus and the Sea of Marmara to the west.
The Ottomans emerged as the principal Muslim adversary to Byzantium and drew in large numbers of nomads and unemployed urbanites seeking a livelihood and aiming to expand Islamic territory. The Ottomans capitalized on the deterioration of the Byzantine frontier defense system, as well as the emergence of economic, religious, and social grievances within the Byzantine Empire. Under the leadership of Osman, and continued by his successors Orhan (Orkhan, ruled 1324-60) and Murad I (1360-89), the Ottomans gradually acquired Byzantine territories, commencing in western Anatolia before expanding into southeastern Europe. It wasn’t until Bayezid I (1389-1402) that the wealth and power acquired through the initial expansion were employed to incorporate the Turkish principalities in Anatolia to the east.
By 1300, Osman governed a region in Anatolia extending from Eskisehir (Dorylaeum) to the plains of İznik (Nicaea), after defeating numerous organized Byzantine attempts to suppress his advancement. Efforts made by the Byzantine Empire to obtain Il-Khanid backing against the Ottomans from the east proved to be fruitless. Moreover, the deployment of mercenary soldiers from Western Europe by the Byzantine emperor led to harming his own territories more than the Turks. Nevertheless, the Ottomans were incapable of capturing the significant cities of Bithynia since they lacked competent siege equipment.
The Ottoman Empire was unable to resist their formidable Turkmen neighbours, including the Aydın and Karası dynasties who had annexed Byzantine lands in the southwest of Anatolia. In 1324 (with some sources providing 1326 as an alternate year), Orhan’s capture of Bursa paved the way for the principality’s evolution into a genuine state, complete with comprehensive administration, superior economic capabilities, and a strong military force. Orhan initiated a military strategy, which subsequent rulers developed, involving the use of Christian mercenary troops to reduce their reliance on nomadic forces.
Orhan swiftly seized the remaining Byzantine towns in the northwestern Anatolia region: Iznik (1331), Izmit (1337), and Uskudar (1338). He subsequently launched an offensive against his prominent Turkmen counterparts to the south. Capitalising on the internal disputes among them, Orhan annexed Karası in 1345 and assumed authority over the region stretching from the Gulf of Edremit to Kapıdağı (Cyzicus), ultimately reaching the Sea of Marmara. He positioned himself to end the profitable monopoly of the city of Aydın, which involved offering mercenary troops to rival Byzantine groups in Thrace and at the Byzantine capital, Constantinople (now Istanbul).
Furthermore, this expansion allowed the Ottomans to supersede Aydın as the primary ally of the Byzantine emperor, John VI Cantacuzenus. The arrival of Ottoman troops in Europe allowed them to perceive the potential for conquest presented by Byzantine decline. Following the death of its ruler, Umur Bey, the fall of Aydın resulted in the Ottomans emerging as leaders among the ghazis opposing the Byzantines. Orhan aided Cantacuzenus in securing the Byzantine throne from John V Palaeologus, which granted him permission to plunder Thrace and marry the emperor’s daughter, Theodora.
Ottoman raiding parties regularly moved through Gallipoli into Thrace, strengthening Ottoman power with the acquisition of huge quantities of booty and luring thousands from the uprooted Turkmen masses of Anatolia into Ottoman service. In 1354, Suleyman, the son of Orhan, transformed Gallipoli, a peninsula on the European side of the Dardanelles, into a permanent expansion base for Europe. Against protests from Cantacuzenus and other dissenting voices, Suleyman refused to leave. Suleyman’s troops advanced from Gallipoli up the Maritsa River into southeastern Europe, carrying out raids as far as Adrianople. Cantacuzenus’s hold on power weakened, partly because of his cooperation with the Turks. Europe gradually woke up to the full scale of the Turkish threat.
Murad I, depicted in a 16th-century miniature painting held at the TOPKAPI PALACE
Museum in Istanbul, was the inaugural Ottoman ruler to achieve permanent conquests in Europe via Gallipoli. Although the defenders of Constantinople were weak and disorganised, the city was bypassed as its fortifications were too robust for the nomadic Ottoman army, which lacked the required siege equipment. Murad’s early conquests proceeded into Thrace, culminating with the 1361 capture of Adrianople, which was the second city of the Byzantine Empire.
The city was renamed Edirne and became the new Ottoman capital, providing the Ottomans with a centre for administrative and military control over Thrace. As the primary stronghold between Constantinople and the Danube River, this fortress regulated the main route of invasion through the Balkan Mountains, ensuring Ottoman possession of their European conquests and fostering additional expansion to the north.
Following this, Murad led an army through the Maritsa River valley and took control of Philippopolis (Philibé or Filibe; modern Plovdiv) in 1363. Control of Constantinople’s primary grain and tax revenues gave the Ottomans the power to force the Byzantine emperor to submit to Ottoman suzerainty. Despite their alliance with Louis I of Hungary and Tsar Shishman of Bulgaria in the first European Crusade against the Ottomans, the death of the Serbian Emperor Stefan Dušan in 1355 left his successors too divided and weak to overcome the Ottomans.
The attempt by John V Palaeologus, the Byzantine emperor, to unite the churches of Constantinople and Rome in order to mobilise European assistance proved unsuccessful. Instead, it further divided Byzantium, resulting in no concrete help from the West. In 1371, Murad was able to rout the allies at Chernomen (Çirmen) on the Maritsa, thereby boosting his confidence and demoralising his smaller enemies. This led them to accept his suzerainty without further resistance.
Murad then integrated numerous European vassals into the rapidly expanding Ottoman Empire. He maintained local native rulers, who accepted his suzerainty, paid annual tributes and supplied contingents for his army, when necessary. This policy allowed the Ottomans to avoid resistance in the region by guaranteeing rulers and subjects that their lives, properties, traditions, and positions would be safeguarded if they peacefully accepted Ottoman rule. This strategy allowed the Ottomans to administer the recently acquired territories without establishing an extensive administrative framework or deploying significant occupation forces.
Murad expedited the consolidation of his empire below the Danube by securing control over Macedonia (1371), central Bulgaria (including Monastir , Sofia , and Niš ), and Serbia. This culminated in the pivotal downfall of the Balkan coalition in 1389 at the Battle of Kosovo. Only Walachia, Bosnia, Albania, Greece, and the Serbian fort of Belgrade remained beyond Ottoman rule to the south of the Danube, and solely Hungary was capable of hindering further Muslim advancements to the north.
Bayezid I, in an undated engraving, succeeded his father after his death during the Battle of Kosovo. Despite his father’s victory, Bayezid I was unable to expand further into Europe and was instead required to restore the defeated vassals and retreat to Anatolia. This was due to the emerging threat posed by the Turkmen principality of Karaman, which was created on the ruins of the Seljuq empire of Anatolia, with its capital at Konya.
Bayezid’s predecessors refrained from forcefully annexing Turkmen territory to focus on Europe. Instead, they pursued peaceful expansion through marriage alliances and the acquisition of territories. By obtaining land in central Anatolia from the emirates of Hamid and Germiyan, the Ottomans established direct contact with Karaman for the first time. Murad was compelled to take military action to prevent occupation of his newly acquired Anatolian territories by an outside force. He later returned to Europe, leaving the problem unsolved for his successor son.
Karaman cooperated with Serbia willingly, inciting opposition to Ottoman rule among Murad’s vassals in both Europe and Anatolia. The opposition fortified the Balkan Union, defeated by the Ottomans in Kosovo, and incited a widespread uprising in Anatolia, which Bayezid was compelled to confront through direct aggression at the earliest opportunity. By 1390, Bayezid had subjugated and absorbed all the other Turkmen emirates in western Anatolia. In 1391, Bayezid invaded and conquered Karaman, annexing multiple Turkmen states situated in eastern Anatolia as he prepared to finalize his conquest in the area. However, a rebellion among some of his Balkan vassals, instigated and supported by Hungary and Byzantium, forced him to abandon his plans and return to Europe to suppress the revolt.
Bayezid swiftly crushed the rebels between 1390 and 1393, took control of Bulgaria, directly governing it for the first time, and laid siege to Constantinople. Hungary responded to the Ottoman threat by embarking on a significant European Crusade. However, Bayezid successfully repelled their efforts at the Battle of Nicopolis (Niğbolu) on the Danube in 1396. Europe was terrorised, and Ottoman control south of the Danube was secured.
Bayezid’s status in the Islamic world was greatly elevated, and he was bestowed with the title of sultan by the shadow Abbasid caliph of Cairo, despite the objections of the caliph’s Mamluk leaders (who governed Egypt, Syria, and the holy cities of Mecca and Medina), who desired to maintain the title for themselves.
Returning to Anatolia to finish the uncompleted conquests against the Crusaders, Bayezid successfully conquered Karaman, the final Turkmen principality, in 1397. Nevertheless, his advancements enticed Timur (Tamerlane), who had established a dominant Tatar empire across Central Asia, Iran, Afghanistan and Mesopotamia.
Timur had previously ceased his invasion of India in 1398 due to his concerns regarding the Ottoman power rising on his western border. Encouraged by Turkmen princes who had sought refuge at his court after their territories were seized by Bayezid, Timur resolved to dismantle Bayezid’s empire before redirecting his focus eastward. Consequently, he invaded Anatolia. During the ensuing confrontation between Bayezid and Timur, the former’s Turkmen vassals and Muslim adherents deserted him due to his abandonment of the traditional Ottoman ghazi practice of advancing against non-Muslims. With only the support of his Christian vassals, Bayezid suffered a decisive defeat by Timur during the Battle of Ankara in 1402. Following his capture, Bayezid died within a year.
Restoration of the Ottoman Empire, 1402–81
Timur aimed for a secure western flank in Anatolia to enable further conquests in the east, rather than conquering the region. After his victory, he retired from Anatolia, having restored the Turkmen princes who had joined him to power. Evidently, Timur assumed that a divided Anatolia would pose no threat to his ambitions.
Bayezid’s sons were able to take control of the family’s former possessions in western Anatolia, while the Ottoman Empire mostly remained unscathed in Europe. Had a strong European Crusade occurred, it could have potentially driven the Ottomans out of Europe. However, due to weakness and division south of the Danube, as well as diversions to other matters to the north, the Ottomans were able to restore what had been previously lost without significant losses.
During the Interregnum (1402-13), Ottoman attempts to regain power were impeded by internal divisions, as Bayezid’s four sons vied for control of the empire. Eventually, Suleyman, Bayezid’s eldest son, established himself as ruler in Europe, establishing a capital at Edirne and garnering support from both Christian vassals and those who had originally inspired Bayezid’s eastern conquests. The Turkmen notables’ descendants, who aided early Ottoman conquests in Europe, endorsed Mehmed’s claims. The backing of Anatolian Muslim religious orders and artisan guilds allowed Mehmed to vanquish and kill his brothers, Mûsa Bey and İsa Bey of Balıkesir in southwestern Anatolia, and Suleyman. As a result, he became Sultan Mehmed (Muḥammad) I with complete control over the empire.