After the Ottoman Turks destroyed the remains of the Byzantine Empire by capturing Constantinople in 1453, they had a strong hold on south-eastern Europe and wanted to expand their power and their religion farther into Europe. The Turks were turned away after an unsuccessful siege of Belgrade in 1456, but Serbia fell to them in 1459, a year after they captured Athens with no resistance. Bosnia accepted Turkish dominance and Islam in 1463, and Albania fell to them in 1479. Hungary, however, kept the Turks at bay into the sixteenth century. In 1514, Hungary declared a crusade against the Turks and called for troops. Massive numbers of peasants responded; once armed, however, they attacked the nobility instead. The suppression of the revolt forced an even more oppressive dominance over the peasantry and left the country open to possible invasion. The Ottoman leader who staged the invasion was Suleiman, called the Wise by his people, the Magnificent by the West. In 1521 he invaded Hungary and captured Szabacs and Belgrade, then turned against the Knights of St. John in Rhodes, whose position threatened Muslim control of the eastern Mediterranean; he secured the island on 1 January 1523. In 1525 Suleiman received a request from Francis I of France, inviting him to invade Hungary in order to weaken the power of Habsburg Emperor Charles V. Turkish forces marched in April 1526, and the pope called for the Christian faithful to resist the Muslim invaders. Martin Luther persuaded his followers not to respond to this call, and even Charles declined to fight. Suleiman’s force of some 75,000 scored a difficult victory at Mohacs, and Christianity suffered a moral defeat as well. Suleiman made Hungary a tributary under the control of Transylvanian John Zapolya.

Zapolya consolidated his power in Hungary, but drew the attention of Ferdinand of Habsburg, who defeated him at Tokay. Zapolya appealed for aid, and Suleiman marched in 1529, bringing 80,000 soldiers; Zapolya provided 6,000. Buda fell after a five-day siege and, aided by a flotilla on the Danube, the Turks approached Vienna in late September. They surrounded the city, and for three weeks bombarded and attempted to mine the walls, but failed to breach them. Suleiman withdrew in mid-October to go into winter quarters, but he was pursued by the Austrians, who harassed him constantly and severely damaged his flotilla at Bratislava.

Suleiman returned in force in 1532, but after inconclusive fighting he retreated. Pressed by Persia to his rear, Suleiman decided to make peace in 1533 with Ferdinand of Habsburg, who had to pay tribute to the Turks, but who gained control of about a third of Hungary. Ferdinand was granted, in Suleiman’s words, an eternal peace if he would but observe it. He did not. At the urging of Charles V, Ferdinand joined other European forces invading Turkish Hungary in 1537. They were defeated and virtually destroyed during their retreat. Suleiman led his army back into Hungary and annexed it to his empire. Ferdinand attacked at Pest in 1542 but was repulsed, and Suleiman entered Austria, armed with a veteran army and an alliance with France. He pillaged throughout the country until 1544, when France abrogated the treaty. Suleiman again made peace with Ferdinand under the terms of their first agreement.

Ferdinand could not leave well enough alone. He invaded Transylvania in 1551 and was repulsed, but he managed to defeat a Turkish counteroffensive. After desultory fighting, the two leaders renewed their treaty in 1562 at the Peace of Prague. The Austrian Habsburgs were at peace, but Suleiman was still engaged in a war with the Holy Roman Empire. When Emperor Maximilian ordered another attack on Hungary, the 72-year-old Suleiman returned to Austria at the head of a 100,000-man army. The Turks won a month-long siege of Szigeth, but Suleiman died just before the city fell, so the Turks returned home.

Upon Suleiman’s death, the Ottoman Empire came under the rule of Selim, known as the Sot. After Selim’s navy was defeated at the battle of Lepanto in 1571, Ottoman power began to decline. Fighting with Austrian and Holy Roman Empire forces in the 1590s weakened the Ottoman hold on Hungary and Turkish possessions in the Balkans. The Thirty Years’ War diverted European attention away from the Balkans until the 1660s, when the Turks returned to advance on Vienna under the leadership of Fazil Ahmed Koprulu Pasha. They were checked at Neuhause in September 1663 and postponed their attack until the following spring, by which time the Austrians were stronger and better prepared. The battle of St. Gotthard Abbey was fought as peace talks were being held, and the Turks were forced to retreat to Belgrade. The Peace of Vasvar, signed in August 1664, called for a 20-year peace and ceded Transylvania to Turkey. After the 20-year truce, the Turks were back in 1683. Hungary was in the process of rebelling against Austria, so the Austrians were pressed by a number of enemies: the Hungarians, Transylvanians, and Turks. Muhammad IV arrived at Vienna in June with 150,000 men to besiege a city defended by a mere 15,000. The Turks had little siege artillery, but they managed to breach the walls in a few places. They could not break through in strength, however, and Vienna was spared by the fortuitous arrival of Pole Jan Sobiesky at the same time a German force marched to help. A mixed Austrian- German-Polish force of 70,000 engaged the Turks outside Vienna on 12 September. After a daylong battle, the Turks fled, and the city was saved. When Sobiesky later pursued the Turks, he captured Grau and much of Hungary, which came under Habsburg control over the next five years.

Suleiman II made the last serious threat toward Habsburg territories in 1690, but his defeat at Szalankemen in 1691 and at Zenta in 1697 ended that endeavor. In January 1699 the two powers signed the Treaty of Karlowitz, which ceded Hungary to Austria and left the Turks in control of Serbia.

The defeat of the Turkish invasions served to consolidate Habsburg control in central and southeast Europe, but also stopped Islam from expanding past the Balkans. The Catholics and Protestants had more than their share of struggles, but Christianity in one form or another would remain the religion of most of Europe. Hungary, under Habsburg rule, was later incorporated into the Austro-Hungarian Empire, but the ethnic struggles of the myriad populations of that region simmered under Habsburg control, and to a great extent, continue to this day.