Outnumbered Viennese defenders held off a superior Ottoman force, establishing the westward limit of Ottoman expansion in Europe.
When Süleyman the Magnificent became the sultan of the Ottoman Empire
In 1521, Süleyman captured the Hungarian fortress of Belgrade, opening the way to the upper Danube. In 1522, he successfully ejected the militant Knights of St. John from the island of Rhodes,
Archduke Ferdinand I of Austria attempted to claim the vacant thrones of Bohemia and Hungary, and the Bohemians elected him king. The majority of the Hungarian nobility, however, did not want a member of the imperial Habsburg family as king. Instead, they elected a Transylvanian prince, John Zápolya, as their leader. A minority of Hungarians chose Ferdinand. Both claimants were crowned king of Hungary and sent missions to Süleyman in 1527 seeking recognition. Ferdinand’s envoy irritated the Turks by demanding return of parts of Hungary conquered by the Ottomans, including Belgrade. The grand vizier sarcastically inquired why he did not ask for Constantinople as well. Süleyman recognized Zápolya as King John I of Hungary, promising him military assistance as a vassal of the Ottomans.
When Ferdinand sent an army into Hungary in 1528 and captured Buda, Süleyman decided to fulfill his pledge to aid John while also attacking Ferdinand’s capital, Vienna. The Ottoman army assembled in the spring of 1529. Süleyman had some eighty thousand combat troops and five hundred cannons, including two hundred huge siege guns. On May 10, the expedition marched north. The spring rains were exceptionally heavy, however; rivers overflowed, sweeping away bridges, and roads became quagmires.
It took the Ottoman army two months to reach Belgrade. Oxen could not move the heavy siege guns over the rutted, muddy roads. Süleyman had to leave his big guns behind and depend on three hundred light cannons. When the Ottomans reached Mohács, John joined them with a troop of six thousand Hungarian Christians. The Janissaries easily took Pest, terrorizing their enemies by massacring the garrison and many of the inhabitants of the city. A full month behind schedule, the main body of the army finally camped outside Vienna on September 27. The terrified defenders trembled at the sight of the huge army, convinced that their attackers numbered more than 300,000.
When Ferdinand heard that Süleyman was moving north, he frantically appealed to his Christian fellow monarchs for help. He received very little assistance. His brother, Holy Roman Emperor Charles V, was fully engaged in Italy, battling Francis I of France, and could not spare any troops. Charles did exert pressure on the Protestant princes of Germany to send aid against the Muslims, but few troops arrived. The most useful help came with the arrival of Niklas Graf Salm, a seventy-year-old professional soldier. He brought with him one thousand German pikemen, experts at handling twelve-foot spears, and seven hundred Spaniards equipped with the latest faster-firing wheel-lock muskets.
Ferdinand went to Linz, 100 miles (161 kilometers) west of Vienna. Although a higher-ranking aristocrat was nominally in command, Salm effectively took charge of the defense. He directed a force of twenty-three thousand infantry, two thousand cavalry, and seventy-five cannons. During the respite provided by the slow progress of the Ottoman army, Salm strengthened Vienna’s fortifications. He repaired as much as he could of the decrepit city wall and had earthen bastions and wooden palisades erected behind the first wall. Three of the four city gates were sealed; only one was left operable to serve as a sally port for the cavalry. Buildings outside the walls were demolished, providing a clear field of fire for artillery.
When the Viennese refused Süleyman’s surrender ultimatum, he ordered his three hundred cannons to bombard the city. The siege artillery he had been forced to abandon on the road would have cracked open the city walls, but the light field guns he brought with him did little harm. When the cannon mouths were elevated, however, the projectiles curved over the walls and damaged many houses. The Viennese retaliated with a cavalry sortie that destroyed two gun emplacements, followed by a night raid on Ottoman tents. Ottoman sources record annihilating an Austrian attack and erecting a pyramid of five hundred heads for the sultan.
Unable to breach the wall with his artillery, Süleyman ordered miners to tunnel under it, planning to explode powder kegs and break the barrier. When a miner of Christian parentage defected and informed Salm of the plans, however, Salm organized counter-miners to head off the Ottoman tunnels, leading to bizarre underground battles between the two groups of miners. On October 5, mines exploded under Vienna’s Salt Gate, opening a breach in the city’s defenses. The Janissaries rushed to exploit the breach, only to be repulsed with heavy losses: Their scimitars proved ineffective against twelve-foot pikes and Spanish muskets. A few days later, a breach at the city’s Carinthian Gate resulted in a similar defeat. The weather grew colder and food supplies were running low. Süleyman decided to try one final assault. The Janissaries launched several attacks on October 14, failing each time to widen an opening in the wall. Two days later, as it began to snow, the Ottomans broke camp and began their retreat to Istanbul.
Süleyman saved face as best he could regarding his defeat, claiming that he had never intended to seize Vienna, but had only sought to find and defeat Ferdinand I. Once it became clear that Ferdinand had fled and would not fight, Süleyman said, he had magnanimously lifted the siege to spare the Viennese people further bloodshed; therefore, the battle was really an Ottoman victory. When he reached Buda, his courtiers and King John congratulated Süleyman on his “victorious” campaign.
The Viennese, meanwhile, celebrated the Turkish withdrawal and claimed their successful defense had saved Europe from Muslim conquest. They asserted that, if Süleyman had captured Vienna, he would have wintered his army in Austria, attacked Germany in the spring, and established garrisons along the Rhine before year’s end.
The Viennese do deserve credit for their valiant defense. The main barriers to Turkish expansion into Europe, however, were the severe Balkan climate and the long distance between Europe and Istanbul, rather than the military prowess of the Europeans. Rainfall levels were high in the early sixteenth century, and winter came early. The viable campaign season lasted little more than six months. Süleyman, however, needed to return to Istanbul each year, because he also faced warfare with Persia that might compel him to suspend European operations and march his army eastward. In 1529, Süleyman’s siege of Vienna lasted only twenty days.
Ottoman logistical problems were formidable. The army’s advance guard regularly destroyed crops and settlements in areas under attack, denying food and other supplies to the enemy, but also preventing the Ottomans from living off the land. The farther the army penetrated, the more difficult it became for pack horses, wagons, and camels to move enough food, gunpowder, and missiles along the rutted, muddy roads created by the massive Ottoman army. After a successful siege, Süleyman might have left a garrison to hold Vienna, but the sultan and the main army would have needed to return to Istanbul through a ravaged countryside.
Süleyman invaded Austria again in 1532 but was held up for a month reducing the border fortress of Güns and never reached Vienna. In 1566, Süleyman died while besieging the Hungarian citadel of Szeged. The Ottomans besieged Vienna a second time more than a century later, in 1683, again failing to capture the city. Vienna became the high-water mark of Ottoman expansion into Europe.
An indirect but significant effect of Süleyman’s campaigns upon European history was their aid to the survival of Lutheranism.
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Clot, André. Suleiman the Magnificent. Translated by Matthew J. Reisz. New York: New Amsterdam Books, 1992. Contains a brief description of the siege from the Ottoman point of view. -
Fichtner, Paula Sutter. Ferdinand I of Austria: The Politics of Dynasticism in the Age of the Reformation. New York: Columbia University Press, 1982. Favorable account of Ferdinand’s struggle with the Ottomans. -
Godwin, John. “Siege of the Moles.” Military History 18 (2001): 46-53. Detailed account of the defense of Vienna. -
Goffman, Daniel. The Ottoman Empire and Early Modern Europe. Cambridge, England: Cambridge University Press, 2002. Places the Ottoman state and its military activity within the context of the sixteenth century European political system. -
Maltby, William. The Reign of Charles V. New York: Palgrave, 2002. A concise explanation of Charles V’s policies regarding Ottoman expansionism.
June 12, 1477-Aug. 17, 1487: Hungarian War with the Holy Roman Empire
1520-1566: Reign of Süleyman
June 28, 1522-Dec. 27, 1522: Siege and Fall of Rhodes
1526-1547: Hungarian Civil Wars
Aug. 29, 1526: Battle of Mohács
Sept. 27-28, 1538: Battle of Préveza
1552: Struggle for the Strait of Hormuz
1559-1561: Süleyman’s Sons Wage Civil War
May 18-Sept. 8, 1565: Siege of Malta
1589: Second Janissary Revolt in Constantinople
1593-1606: Ottoman-Austrian War