The classical age of the empire reached its peak under two sultans in the sixteenth century. Selim the First, who ruled from 1512 to 1520, turned the empire eastward and southward with ferocious speed. He defeated the Safavid ruler of Persia at the Battle of Chaldiran in 1514, then swept through Egypt, the Levant, and western Arabia, taking the holy cities of Mecca and Medina under Ottoman protection. With that, Selim assumed the Caliphate, making the Ottoman sultan not merely a political ruler but the spiritual leader of Sunni Islam worldwide. In eight years of campaigning, he roughly doubled the empire's size.

His son Suleiman, who would be called the Magnificent by Europeans and the Lawgiver by his own people, inherited this enlarged empire in 1520 and spent forty-six years expanding it further. He captured Belgrade in 1521. At Mohács in 1526 he crushed the Hungarian army and effectively absorbed the kingdom. He laid siege to Vienna in 1529 but was forced to withdraw by the onset of winter. He tried again in 1532 and was again turned back. Vienna marked the furthest point an Ottoman army could march from Istanbul within a single campaigning season, and the city held that status as the empire's permanent western limit.

In the east, Suleiman took Baghdad from the Persians in 1535, securing Mesopotamia and access to the Persian Gulf. His admiral Barbarossa, commanding the Ottoman fleet in the Mediterranean, won major victories at Preveza in 1538 and Djerba in 1560, seized Rhodes and Tripoli from the Knights of Saint John, and even seized Nice in a joint venture with France in 1543. France and the Ottoman Empire had become formal allies, bound by mutual opposition to the Habsburg dynasty that ruled both Spain and Austria. The sultan granted French merchants the right to trade within the empire without taxation. The Ottomans were not merely a threat to Europe; they were a participant in European politics.

By the end of Suleiman's reign the empire stretched from the Persian Gulf in the east to Algeria in the west, from Yemen in the south to Hungary and parts of Ukraine in the north, and held a population of roughly fifteen million people. It was the largest and most powerful state in the world that straddled Europe and Asia. Suleiman died of natural causes in his tent during the Siege of Szigetvár in 1566, still in the field at the age of seventy-one.

The limits of Ottoman expansion became clearer in the decades after Suleiman. In the summer of 1565, a massive Ottoman force of around fifty thousand men besieged the island of Malta, held by the Knights of Saint John and a Maltese garrison of a few thousand. The siege lasted the whole summer. The Maltese held. The Ottomans withdrew in September having failed to take the main fortifications, a rare and stinging defeat. Six years later, at the Battle of Lepanto in October 1571, a coalition of Catholic powers destroyed the Ottoman fleet in a single afternoon. The psychological shock was enormous.

The Ottomans rebuilt their fleet within months, famously boasting that the Europeans had merely shaved off their beard, and recovered Tunisia from Spain in 1574. But Lepanto had exposed something real: the experienced officers and sailors who died in the battle could not be replaced as quickly as the ships. Meanwhile, the Portuguese discovery of the Cape of Good Hope in 1488 had already begun redirecting the spice trade around Africa, eroding the revenue the Ottomans derived from controlling the overland routes between Europe and Asia. The empire's economic foundation was shifting beneath it.

At home, the pressures mounted. The population had reached around thirty million by 1600, straining land and resources. Changes in European military tactics made the traditional Ottoman cavalry less effective. The Long War against Austria from 1593 to 1606 forced the empire to recruit larger infantry forces, and when those soldiers were demobilised they turned to banditry, setting off a wave of rural uprisings known as the Jelali revolts that spread anarchy across Anatolia between 1595 and 1610. The empire was not yet in decline, but the strain of governing so vast a territory was beginning to show.

The seventeenth century brought new instabilities at the centre. A period historians call the Sultanate of Women saw the mothers of young or weak sultans exercise real political power on behalf of their sons. The inadequacy of Sultan Ibrahim the First, who ruled from 1640 to 1648, and the minority accession of a child sultan in 1646 created a genuine crisis of authority. The two most powerful figures of this era were Kösem Sultan and her daughter-in-law Turhan Hatice, whose rivalry for control of the imperial court culminated in Kösem's murder in 1651. The palace had become a theatre of lethal competition.

The empire was rescued, temporarily, by a dynasty of grand viziers. In September 1656, an elderly but iron-willed administrator named Köprülü Mehmed Pasha accepted the seals of office from the valide sultan Turhan Hatice, on the condition that he would have unprecedented authority and freedom from interference. He used that authority ruthlessly: purging rivals, reasserting central control, and restoring military discipline. His son Köprülü Fazıl Ahmed succeeded him as grand vizier in 1661 and continued the work, completing the conquest of Crete in 1669 and expanding Ottoman control into southern Ukraine by 1676. For a generation, the empire looked renewed.

Then came 1683. Grand Vizier Kara Mustafa Pasha led a huge army westward in May of that year, aiming at a second siege of Vienna. The Ottoman force was the largest assembled in Europe in a century. But Kara Mustafa delayed the final assault too long. On 12 September 1683, a relief army of Habsburg, German, and Polish forces under the Polish king Jan attacked from the hills above Vienna. The Ottoman camp collapsed. It was the most decisive Ottoman defeat in a generation, and the beginning of a long retreat.

The Holy League pressed its advantage without pause for sixteen years. Fortress after fortress fell. Province after province was lost. The reckoning came at the Treaty of Karlowitz, signed on 26 January 1699. For the first time in the empire's history, the Ottomans surrendered control of significant European territories permanently, including most of Hungary. The empire had reached the end of its expansionist era. From this point forward, it would fight defensive wars in Europe, trying to hold what remained rather than add to it.

The eighteenth century brought new threats from a new direction. Russia under Peter the Great and his successors was expanding southward toward the Black Sea and the Caucasus, pressing on Ottoman territory in ways the empire had never faced from that quarter. The Swedish king Charles the Twelfth, defeated by the Russians at the Battle of Poltava in 1709, fled to the Ottoman Empire and persuaded Sultan Ahmed the Third to declare war on Russia, which produced a rare Ottoman victory at the Pruth River in 1711. But the broader trend was ominous. A series of wars with Russia across the eighteenth century demonstrated that the empire was falling behind technologically and militarily.

The Tulip Era, roughly 1718 to 1730, offered a brief respite. Named for Sultan Ahmed the Third's passion for the tulip flower, it was a period of relative peace, cultural flowering, and tentative engagement with European ideas. Baroque and Rococo influences appeared in Ottoman architecture, most visibly in the ornate Fountain of Ahmed the Third outside the Topkapı Palace. In 1726, an official named Ibrahim Muteferrika persuaded the grand vizier and the sultan to permit the printing of non-religious books in Turkish, and by 1743 his press had produced seventeen works. It was a small but significant opening, arriving nearly three centuries after Gutenberg.

The empire's military reformers faced fierce resistance. When an artillery school was established with French instructors in 1734 to teach European gunnery methods, the religious establishment shut it down on theological grounds. It did not reopen until 1754. Sultan Selim the Third, who came to power in 1789, made the first serious attempt to modernise the Ottoman army along European lines. The Janissaries, the empire's elite infantry corps, had grown from a disciplined force into an entrenched, conservative institution jealous of its privileges and violently opposed to any change that threatened them. They revolted. Selim was deposed and killed.

His successor, Mahmud the Second, learned from that failure. He spent years preparing the ground, building loyalty among officers who could be trusted, and waiting for the right moment. In 1826, he moved against the Janissaries with artillery, bombarding their barracks in Istanbul and destroying the corps in a single violent episode that became known as the Auspicious Incident. The Janissaries were gone. The path to reform was open, at a cost of thousands of lives.

The reform era that followed, called the Tanzimat, meaning organisation, ran from 1839 to 1876 and amounted to the most thoroughgoing attempt to rebuild the Ottoman state from the inside. The government introduced a modern conscript army, a banking system, secular law codes replacing religious courts, and a reformed tax structure. Paper banknotes appeared in 1840. The first telegraph line ran between Istanbul and Edirne from 1847. Railways began in 1856. In 1856 the Hatt-ı Hümayun, a formal imperial decree, promised equality for all Ottoman subjects regardless of religion or ethnicity. It was a sweeping promise that the empire would struggle to keep.

The Tanzimat reforms could not dissolve the force of nationalism. Across the Balkans, subject peoples who had maintained their own languages, religions, and identities for centuries began demanding their own states. The Serbian revolution erupted in 1804 and by 1817 had produced a self-governing Serbian monarchy. The Greeks declared war on the sultan in 1821, and by 1829 the First Hellenic Republic had been formally recognised as independent, the first Balkan state to break free. Then came Romania, Bulgaria, Montenegro, and others. Each war, each treaty, each congress in a European capital shaved another piece from the Ottoman map.

The Crimean War of 1853 to 1856 illustrated the empire's new dependence on European patrons. Britain and France intervened militarily to defend Ottoman territory against Russian expansion, and the subsequent Treaty of Paris secured Ottoman control of the Balkans and the Black Sea basin. But the empire had taken its first foreign loan in August 1854 to finance the war, and the habit of borrowing would not stop. The war also displaced enormous populations: around two hundred thousand Crimean Tatars fled to Ottoman territory, and tens of thousands of Circassians were driven from the Caucasus and settled in Anatolia. The empire was becoming a refuge for the Muslim populations Europe was displacing.

The Congress of Berlin in the summer of 1878, convened after Russia had crushed the Ottomans in the war of 1877 to 1878, formalised the empire's diminishment. Bulgaria became an autonomous principality. Romania, Serbia, and Montenegro gained full independence. Austria-Hungary occupied Bosnia and Herzegovina. Britain took administrative control of Cyprus. France occupied Tunisia in 1881. The European powers were carving up the Ottoman periphery, and the empire's leaders could only negotiate the terms of each loss. European statesmen called it openly the sick man of Europe.

From 1894 to 1896, Sultan Abdülhamid the Second deployed irregular cavalry units, mostly recruited from Kurdish tribesmen, against the Armenian population of eastern Anatolia. The massacres that followed killed somewhere between one hundred thousand and three hundred thousand Armenians. Armenian activists seized the Ottoman Bank in Istanbul in 1896 to draw European attention to the killings, but no intervention followed. The massacres remained unpunished and the grievances unresolved, a wound that would tear open again with catastrophic force twenty years later.

The empire's last political transformation came on 3 July 1908, when the Young Turk Revolution forced Sultan Abdülhamid to restore the constitution of 1876 and reconvene parliament. The reformers who drove the revolution were organised under the Committee of Union and Progress, and they believed that a modernised, constitutionally governed Ottoman state could survive in the twentieth century. For a moment, crowds in Istanbul celebrated in the streets, Muslims and Christians embracing. The moment did not last. The Committee of Union and Progress splintered, rivalries hardened, and by 1913 a coup had placed a tight nationalist leadership, known as the Three Pashas, in full control of the state.

The Balkan Wars of 1912 and 1913 were a catastrophe. Bulgaria, Serbia, Greece, and Montenegro attacked simultaneously and drove the Ottomans out of nearly all of their remaining European territory. The ancient capital of Edirne fell. Around four hundred thousand Muslims fled westward with the retreating army. In two years, the empire lost most of what it had held in Europe for five centuries. By 1914 the Ottoman state controlled little more than Anatolia, the Arab provinces, and a strip of eastern Thrace. The loss was not just territorial: it was psychological.

In August 1914, the Young Turk government signed a secret alliance with Germany. The empire was dragged into the war in late October when two German warships, nominally transferred to the Ottoman Navy but still under German command, shelled the Russian port of Sevastopol. Russia, Britain, and France all declared war on the empire. There were real Ottoman victories in the early years: the defence at Gallipoli in 1915 repulsed a major Allied amphibious assault, and a besieged British force at Kut in Mesopotamia surrendered in April 1916. But the Caucasus campaign against Russia was a disaster, and the Arab Revolt that began in 1916 turned the southern front against the Ottomans.

In 1915, as Russian forces advanced into eastern Anatolia supported by Armenian volunteer units, the Ottoman government issued orders deporting the Armenian population of the eastern provinces southward into Syria and Mesopotamia. The deportations were accompanied by mass killings. Estimates of the total Armenian death toll range from three hundred thousand to one and a half million; the scholarly consensus places the figure in the hundreds of thousands at minimum. The killings are recognised by most historians and by many governments as genocide. They remain among the most contested and consequential acts in the empire's final years.

The armistice came on 30 October 1918. Allied warships anchored in the Bosphorus. Allied troops occupied Istanbul. The Three Pashas fled the country. Under the Treaty of Sèvres in 1920, the empire was to be partitioned: Greece would take much of western Anatolia, France and Britain the Arab provinces, and an independent Armenian state would be carved from the east. The empire was to be reduced to a rump. Thirty-nine new countries would eventually be created from its former territories.

But the partition never fully happened. A military commander named Mustafa Kemal Pasha organised resistance in Anatolia, rallying the remnants of the Ottoman army and fighting a new war against the Greek forces advancing from the coast. The Turkish War of Independence ran from 1919 to 1923. Kemal drove the Greek army into the sea at Smyrna in September 1922, and the Allied powers, recognising the new reality, abandoned the Treaty of Sèvres.

The sultanate was abolished on 1 November 1922 by the Grand National Assembly meeting in Ankara. Two weeks later, on 17 November 1922, the last sultan, Mehmed the Sixth, boarded a British warship in Istanbul and sailed away into exile. He carried almost nothing. The dynasty that had ruled from Osman's dream in 1299 to that grey November morning on the Bosphorus was over. The Treaty of Lausanne, signed on 24 July 1923, gave international recognition to the new Turkish state. On 29 October 1923, the Republic of Turkey was formally declared. The caliphate, the empire's claim to spiritual leadership over Sunni Islam, was abolished on 3 March 1924. The sultan and his family were declared personae non gratae and exiled permanently.

The last man born as a subject of the Ottoman Empire and belonging to the ruling dynasty was a figure named Ertuğrul Osman, grandson of Sultan Abdülhamid the Second. He lived in New York for decades, carrying himself as a citizen of a state that no longer existed. When an interviewer asked him whether he wished the empire to be restored, he said simply no. Democracy, he said, works well in Turkey. He returned to Istanbul in 1992 for the first time since the exile, took Turkish citizenship in 2002, and died there in September 2009 at the age of ninety-seven. With him went the last living memory of the empire as a lived reality.

What the Ottoman Empire left behind was not a single country but a world. The thirty-nine states that emerged from its territory stretched from Hungary to Yemen, from Algeria to Iraq. The customs, cuisines, legal traditions, and architectural forms of the Middle East and southeastern Europe still carry the Ottoman imprint six hundred years later. The minarets of Istanbul, the coffee houses of the Balkans, the administrative structures of the Arab world, the contested borders of the modern Middle East: all of these are, in some measure, the empire's legacy.

The Tanzimat reformers who tried to save the empire in the nineteenth century trained, in their schools and academies, the generation that would build the Republic of Turkey. Mustafa Kemal Atatürk, who abolished the sultanate and founded the republic, had been educated in precisely those institutions. The empire's final act was to produce its own successor.

What the six centuries add up to is this: an empire that began as a dream in a small chieftain's tent outlasted every rival it faced in its prime, bent the course of European history at Vienna and Lepanto and Constantinople, and died not in a single catastrophic defeat but in the slow accumulation of a hundred losses, each one manageable, until the whole was gone. Osman's tree, the one from the dream, had roots in three continents. When the last sultan sailed away on that November morning, the tree was still standing in the form of a new republic, its branches stripped, its roots intact, drawing water from the same ancient soil.