Ottoman wars in Europe

“Ottoman wars in Europe” is a collective name for the many wars the Ottoman Empire fought against European states. They were not one war but dozens of campaigns over more than three centuries, with long periods of peace in between. In broad terms there were two phases: a phase of expansion, from the 1350s to the 1560s, when the Ottomans conquered the Balkans and most of Hungary; and a phase of stalemate and then retreat, from the late sixteenth century onward, which accelerated after the failed siege of Vienna in 1683.

The Ottoman state began around 1300 as a small principality in north-western Anatolia, named after its founder Osman. It was one of several Turkish Muslim principalities that emerged as the Seljuk and Byzantine states weakened. Within 150 years it had become an empire straddling Asia and Europe, and in the sixteenth century it was one of the most powerful states in the world.

For Europeans, especially in the Balkans and Central Europe, the Ottoman advance was a central experience of the late Middle Ages and early modern period. For the Ottomans, war in Europe was part of a broader imperial project that also involved wars with Safavid Iran, the Mamluks of Egypt and states in the Mediterranean.

In the mid-fourteenth century the Balkans were politically fragmented. The Byzantine Empire, once a great power, had shrunk to a few territories around Constantinople and was torn by civil wars. The Serbian empire of Stefan Dušan broke apart after his death in 1355, and Bulgaria was divided. Rival Byzantine claimants even hired Ottoman troops, which gave the Ottomans experience in Europe. In 1354, after an earthquake damaged its walls, the Ottomans occupied the fortress of Gallipoli on the European shore of the Dardanelles.

Why did the Ottomans keep expanding? Historians give several reasons. Ottoman rulers drew prestige from the Islamic ideal of ghaza (war against non-Muslims), but they were also pragmatic state-builders who wanted land, revenue and loyal soldiers. Conquered land was divided into timars, grants whose revenues supported cavalrymen, so expansion rewarded the military class. Rich trade routes, silver mines in Serbia and Bosnia, and the prestige of Constantinople itself were additional attractions.

European resistance was weakened by rivalry. Catholic and Orthodox Christians distrusted each other, especially after the Fourth Crusade had sacked Constantinople in 1204. Venice and Genoa competed for trade and sometimes made deals with the Ottomans. Later, France allied with the Ottomans against the Habsburgs, and the Protestant Reformation divided Christian Europe further.

The Ottoman army combined provincial cavalry (sipahis supported by timars) with a salaried standing army at the sultan's court. The most famous part of this standing army was the Janissary infantry, recruited through the devshirme, a levy of Christian boys from Balkan villages who were converted to Islam and trained as soldiers or administrators. The Ottomans also made early and effective use of gunpowder artillery and firearms, and they were skilled at logistics, building roads, bridges and supply depots. Light raiding cavalry (akıncıs) and, later, the Tatars of the Crimean Khanate carried out raids deep into enemy territory.

Their opponents changed over time. In the fourteenth century they were Byzantium, Serbia, Bulgaria and local Balkan lords. In the fifteenth century the kingdom of Hungary, with commanders like John Hunyadi, became the main barrier, alongside Venice at sea and rebels such as the Albanian leader Skanderbeg. From the 1520s the Habsburg dynasty, ruling Austria, Bohemia, parts of Hungary and, under Charles V, Spain, became the Ottomans' chief rival. Poland–Lithuania, Russia and a series of papal “Holy Leagues” also fought them.

Many people crossed the religious divide. Christian Balkan lords served as Ottoman vassals and fought in Ottoman armies; Serbian knights fought for Sultan Bayezid I at Ankara in 1402. Renegades from across Europe served the sultan, and Hungarian nobles sometimes sought Ottoman protection against the Habsburgs.

After taking Gallipoli, the Ottomans moved into Thrace and made Edirne (Adrianople) their European capital. In 1371 they defeated Serbian lords at the Battle of Maritsa. In 1389, at the Battle of Kosovo, an Ottoman army met a Serbian-led coalition under Prince Lazar. Both Lazar and Sultan Murad I died; the battle was militarily inconclusive, but Serbia became an Ottoman vassal soon afterward. Bulgaria was annexed in the 1390s.

Alarmed, Western Europe organised a crusade. In 1396 a Hungarian, French and Burgundian army under King Sigismund of Hungary was crushed by Sultan Bayezid I at Nicopolis on the Danube. The Ottoman advance was interrupted not by Europeans but by the Central Asian conqueror Timur (Tamerlane), who defeated and captured Bayezid at Ankara in 1402. A decade of civil war among Bayezid's sons followed, but the state recovered.

In 1444 another crusade, led by King Władysław of Poland and Hungary and John Hunyadi, was defeated at Varna on the Black Sea coast; the young king was killed. Then, on 29 May 1453, after a siege of about seven weeks, Sultan Mehmed II captured Constantinople. The last Byzantine emperor, Constantine XI, died in the fighting. Mehmed's army used huge bronze cannons to batter the ancient land walls and moved ships overland into the Golden Horn. The city, soon called Istanbul, became the Ottoman capital, and Mehmed became known as Fatih, “the Conqueror”.

Mehmed II completed the conquest of Serbia (1459), Bosnia (1463) and most of Albania after Skanderbeg's death (1468), but failed to take Belgrade, which Hunyadi defended in 1456. In the early sixteenth century Sultan Selim I turned east, conquering the Mamluk sultanate of Egypt and Syria in 1516–1517, which doubled the empire's size and wealth. His son Suleiman I (known in Europe as “the Magnificent” and in Turkey as Kanuni, “the Lawgiver”) then turned back to Europe, taking Belgrade in 1521 and Rhodes from the Knights of St John in 1522.

On 29 August 1526, at Mohács in southern Hungary, Suleiman's army destroyed the Hungarian royal army in a few hours. King Louis II drowned while fleeing. The Hungarian kingdom split between rival claimants, one backed by the Habsburgs and one by the Ottomans. In 1529 Suleiman besieged Vienna, the Habsburg capital, but late autumn weather, long supply lines and stubborn defence forced him to withdraw. In 1541 the Ottomans annexed central Hungary around Buda, and for 150 years Hungary was divided into three parts: Habsburg “Royal Hungary” in the west and north, Ottoman Hungary in the centre, and the semi-independent principality of Transylvania under Ottoman overlordship.

At sea the Ottomans became a major naval power, aided by corsairs such as Hayreddin Barbarossa, and they won a great victory at Preveza in 1538. But they failed to capture Malta in 1565. In 1570–1571 they conquered Venetian Cyprus, and in October 1571 a Holy League fleet of Spain, Venice and the Papacy destroyed the Ottoman fleet at Lepanto. Lepanto was celebrated all over Catholic Europe, but the Ottomans rebuilt their fleet within a year and kept Cyprus, so historians debate how decisive it really was.

From the late sixteenth century the frontier in Hungary became a zone of fortresses and constant small-scale raiding. The “Long Turkish War” of 1593–1606 ended in the Peace of Zsitvatorok, in which the sultan treated the Habsburg emperor as an equal for the first time. In the seventeenth century the Ottomans still made gains, taking Crete from Venice after a siege of Candia (Heraklion) that lasted more than twenty years and ended in 1669, and advancing into Ukraine against Poland.

In 1683 the grand vizier Kara Mustafa Pasha led a huge army to besiege Vienna a second time. After two months of siege the city was near collapse, but on 12 September a relief army of Imperial, Polish and German troops, with King John III Sobieski of Poland leading the decisive cavalry charge, routed the Ottomans at the Battle of Vienna (Kahlenberg). Kara Mustafa was executed on the sultan's orders.

A new Holy League of the Habsburgs, Poland, Venice and later Russia went on the offensive in the Great Turkish War (1683–1699). The Habsburgs recaptured Buda in 1686 and won a great victory at Zenta in 1697 under Prince Eugene of Savoy. In the Treaty of Karlowitz (1699) the Ottomans gave up most of Hungary and Transylvania to the Habsburgs and other lands to Venice and Poland. This is usually treated as the end of the classic Ottoman wars in Europe, though wars with Austria and especially Russia continued through the eighteenth and nineteenth centuries, and the Balkan nations won independence between 1804 and 1913.

There are no reliable overall casualty figures. Contemporary sources give army sizes and battle deaths that are often exaggerated, especially in European pamphlets and Ottoman victory proclamations. Most historians avoid any total and instead stress the long-term effects of war on frontier populations.

For ordinary people, the worst suffering often came from raids rather than great battles. Ottoman akıncı cavalry and Crimean Tatar raiders carried off very large numbers of captives from Hungary, Croatia, Austria, Poland–Lithuania and Russia to be sold in slave markets; Christian forces, including the Habsburg frontier troops, Venetian fleets and the Knights of Malta, also enslaved Muslims. Estimates for the Tatar slave trade alone run into the hundreds of thousands or more over several centuries, but they are uncertain. The sack of Constantinople in 1453 lasted three days, with killing, looting and enslavement of many inhabitants.

War also caused large migrations. Many Balkan Christians fled north; during the Great Turkish War tens of thousands of Serbs moved into Habsburg Hungary in the “Great Migration” of 1690. Conversely, Muslims left Hungary after 1699 and the Balkans in later centuries. The devshirme took boys from Christian families, a painful experience remembered in Balkan folklore, although some families saw it as a route to high office. Parts of the Hungarian plain were depopulated during a century and a half of frontier war.

The most lasting result was centuries of Ottoman rule in south-eastern Europe. Ottoman society organised people partly by religion: Orthodox Christians, Armenians and Jews had their own religious leaders and courts, an arrangement historians later described as the millet system. Many Bosnians, Albanians and others converted to Islam over generations, creating Muslim communities in Europe that still exist. Sephardic Jews expelled from Spain in 1492 found refuge in Ottoman cities such as Thessaloniki and Istanbul.

For Central Europe, the Ottoman threat helped shape the Habsburg monarchy. The need to defend the frontier encouraged the Habsburgs to create the Military Frontier (Militärgrenze), a fortified border zone settled by soldier-farmers, many of them Serbs and Croats. The fall of Constantinople also sent Greek scholars and manuscripts to Italy, contributing, alongside earlier contacts, to the study of Greek in the Renaissance.

The wars also transformed diplomacy. France's alliance with the Ottomans in the 1530s showed that religious unity no longer determined European politics. Trade privileges (capitulations) granted to European states were at first a sign of Ottoman strength, but in later centuries they became tools of European influence. After 1699 the “Eastern Question”, what would happen to Ottoman lands as the empire weakened, became a central issue of European politics until the First World War.

In Turkey, the conquest of Istanbul in 1453 is celebrated as a glorious turning point; the anniversary on 29 May is marked each year, and Mehmed II and Suleiman are national heroes. The Ottoman expansion is often presented as a story of just rule and tolerance, a view historians find partly true but also idealised. In the Balkan countries, by contrast, national histories written in the nineteenth and twentieth centuries, during struggles for independence, often described Ottoman rule as the “Turkish yoke”, a long period of oppression and stagnation.

Serbian memory centres on the Battle of Kosovo (1389), turned by epic songs into a story of heroic sacrifice; it became a powerful and sometimes dangerous political symbol, invoked most notoriously in the 1980s and 1990s. In Albania, Skanderbeg is the national hero. Greeks remember the fall of Constantinople and the period of Tourkokratia (“Turkish rule”) as a national tragedy. Bosnian Muslims and Albanians, many of whose ancestors converted, have more mixed memories.

In Hungary, Mohács is remembered as a national catastrophe; the Hungarian saying “more was lost at Mohács” is still used to console someone that a setback could have been worse. In Austria, the defence of Vienna in 1529 and especially 1683 became a symbol of saving “Christian Europe”, and Poles remember Sobieski's charge with pride as proof of Poland's role as a “bulwark of Christendom” (antemurale christianitatis). Popular legends, such as the story that the croissant or Viennese coffee houses were born from the 1683 siege, are not supported by evidence. In recent decades these memories have again been used in political debates about Islam and Europe, while historians emphasise exchange, coexistence and the complexity of Ottoman rule.

Ottoman sources include chronicles such as those of Aşıkpaşazade (fifteenth century) and later official histories, campaign diaries, imperial decrees and, very importantly, tax registers (tahrir defterleri), which list villages, households and revenues in conquered provinces. These registers let historians study population, settlement and conversion in the Balkans in detail, although they record taxpayers, not everyone, and have to be interpreted carefully. The seventeenth-century traveller Evliya Çelebi left a vast travel account including the Balkans and the Habsburg frontier.

Byzantine historians of the fifteenth century, including Doukas, George Sphrantzes, Laonikos Chalkokondyles and Kritoboulos of Imbros (who wrote for Mehmed II), describe the fall of Constantinople from different angles. Western sources include Venetian diplomatic reports (relazioni), the letters of the Habsburg ambassador Ogier Ghiselin de Busbecq from Suleiman's court, and captives' memoirs, such as the account of Konstantin Mihailović, a Serb who served in the Janissaries. Pamphlets printed in Germany about the “Turkish menace” (Türkenschriften) shaped public opinion but are propaganda, not neutral reports.

Each body of sources has its biases: Ottoman chronicles celebrate the dynasty, Christian texts often describe Ottomans as a divine punishment, and numbers everywhere are inflated. Modern historians combine them with archival material from Istanbul, Vienna and Venice, and with archaeology of fortresses and battlefields.

Why did the early Ottomans expand so successfully? In 1938 Paul Wittek proposed the “ghazi thesis”: the Ottoman state was born as a community of holy warriors dedicated to war against Christians. Later historians challenged this. Cemal Kafadar's Between Two Worlds (1995) argued that frontier identity was fluid, that ghaza was compatible with alliances with Christians, and that the early Ottomans were pragmatic; Heath Lowry and others stressed cooperation with Byzantine and Balkan elites. Most historians now see religious ideology, opportunity and state-building working together.

A second debate concerns the “decline thesis”, the older view that the Ottoman Empire began a long decline after Suleiman's death in 1566, explaining its military defeats. Many historians now reject this as too simple. They describe instead a transformation in the seventeenth century, with changing military organisation, taxation and politics, and note that the empire could still win wars, as at Candia. The defeat of 1683–1699 is therefore explained by specific factors, including military reforms in Habsburg and Russian armies, coalition warfare and Ottoman overextension, rather than by general decay.

Historians also question the image of a permanent “clash of civilisations” between the Ottoman Empire and Europe. Gábor Ágoston and others show that the Ottomans were part of the European state system, fought with similar military technology, made alliances with Christian powers and competed for the same resources. At the same time, historians of the Balkans insist that the realities of conquest, slavery, the devshirme and unequal status for non-Muslims should not be minimised. Balanced accounts try to hold both sides of this picture together.