Siege of Vienna (1529)

The Siege of Vienna, from 27 September to 15 October 1529, was the first Ottoman attempt to take the Habsburg capital. Sultan Suleiman the Magnificent arrived before the city with a very large army, but bad weather, lost artillery and a determined garrison forced him to withdraw after less than three weeks. The failure marked roughly the limit of Ottoman expansion into Central Europe and opened a long Habsburg–Ottoman rivalry.

The siege grew out of the Battle of Mohács in 1526, where King Louis II of Hungary was killed. Two rivals claimed his crown: the Habsburg Archduke Ferdinand of Austria, brother of the emperor Charles V, and the Hungarian magnate John Zápolya. Ferdinand drove Zápolya out of Buda in 1527, and Zápolya turned to Suleiman, accepting Ottoman overlordship in return for support. Suleiman's campaign of 1529 aimed at least to restore his vassal and to strike at Ferdinand; whether he seriously intended to hold Vienna is debated by historians.

Suleiman mustered his army in the spring of 1529. Contemporary writers gave huge figures for his army, but modern estimates of the fighting force that reached Vienna range from about 75,000 to 100,000 men. The spring was unusually wet. Floods and mud slowed the march through the Balkans, and much of the heavy siege artillery had to be left behind, while many camels died and sickness spread among the troops. Zápolya joined the sultan at Mohács in August, and Buda was retaken in early September.

Vienna's medieval walls were old and in places thin. Command of the defence fell largely to Count Niklas Salm, a veteran mercenary officer of about seventy, supported by German landsknechts, Spanish arquebusiers and local militia, probably no more than around 20,000 men in total. Salm blocked the gates, strengthened the walls with earthworks and an inner rampart, and cleared buildings to make room for the defences.

The Ottoman army reached the city in late September, weakened by the march and lacking heavy guns. It relied instead on mines dug beneath the walls. The defenders found and destroyed several tunnels and made sorties against the diggers, though one large sortie on 6 October suffered heavy losses. Further rain fell, supplies ran short, and discontent grew among the Janissaries. After a council of war, Suleiman ordered a final assault on 14 October, which was beaten back. The next day he lifted the siege. The retreat through early snow and mud was costly, and the army reached Constantinople only in December. During the campaign Ottoman irregular troops ravaged the surrounding countryside, killing many civilians and carrying thousands into slavery. Salm was wounded in the last assault and died the following year.

The campaign left Zápolya in control of Buda as an Ottoman vassal, so in Hungary Suleiman's position was stronger than before. But Vienna had held. A second campaign in 1532 was delayed by the small fortress of Kőszeg and never reached the city. Hungary became a long-running battleground between the Habsburg Monarchy and the Ottoman Empire, and the Ottomans did not return to besiege Vienna until 1683, when their defeat at the Battle of Vienna began their retreat from Central Europe.

Our 1530 map shows the situation just after the siege, with Vienna inside the Holy Roman Empire and much of Hungary on the Ottoman side.