Suleiman the Magnificent - Wikipedia

On August 21, 1541, Ottoman Turks under Suleiman the Magnificent captured Buda, the capital of the Hungarian Kingdom and went on to dominate central Hungary for 150 years. From the article:

Upon succeeding his father, Suleiman began a series of military conquests, eventually suppressing a revolt led by the Ottoman-appointed governor of Damascus in 1521. Suleiman soon made preparations for the conquest of Belgrade from the Kingdom of Hungary—something his great-grandfather Mehmed II had failed to achieve because of John Hunyadi's strong defense in the region. Its capture was vital in removing the Hungarians and Croats who, following the defeats of the Albanians, Bosniaks, Bulgarians, Byzantines and the Serbs, remained the only formidable force who could block further Ottoman gains in Europe. Suleiman encircled Belgrade and began a series of heavy bombardments from an island in the Danube. Belgrade, with a garrison of only 700 men, and receiving no aid from Hungary, fell in August 1521.[19]

The fall of Christendom's major strongholds spread fear across Europe. As the ambassador of the Holy Roman Empire to Constantinople was to note, "The capture of Belgrade was at the origin of the dramatic events which engulfed Hungary. It led to the death of King Louis, the capture of Buda, the occupation of Transylvania, the ruin of a flourishing kingdom and the fear of neighboring nations that they would suffer the same fate ..."[20]

The road to Hungary and Austria lay open, but Suleiman turned his attention instead to the Eastern Mediterranean island of Rhodes, the home base of the Knights Hospitaller. In the summer of 1522, taking advantage of the large navy he inherited from his father, Suleiman dispatched an armada of some 400 ships towards Rhodes, while personally leading an army of 180,000 across Asia Minor to a point opposite the island itself.[21] Here Suleiman built a large fortification, Marmaris Castle, that served as a base for the Ottoman Navy. Following the brutal five-month Siege of Rhodes (1522), Rhodes capitulated and Suleiman allowed the Knights of Rhodes to depart.[22] The conquest of the island cost the Ottomans 50,000[23][24] to 60,000[24] dead from battle and sickness (Christian claims went as high as 64,000 Ottoman battle deaths and 50,000 disease deaths).[24]

As relations between Hungary and the Ottoman Empire deteriorated, Suleiman resumed his campaign in Central Europe, and on 29 August 1526 he defeated Louis II of Hungary (1506–26) at the Battle of Mohács. In its wake, Hungarian resistance collapsed, and the Ottoman Empire became the preeminent power in Central Europe.[25] Upon encountering the lifeless body of King Louis, Suleiman is said to have lamented: "I came indeed in arms against him; but it was not my wish that he should be thus cut off before he scarcely tasted the sweets of life and royalty."[26] While Suleiman was campaigning in Hungary, Turkmen tribes in central Anatolia (in Cilicia) revolted under the leadership of Kalender Çelebi.[27]

Some Hungarian nobles proposed that Ferdinand, who was ruler of neighboring Austria and tied to Louis II's family by marriage, be King of Hungary, citing previous agreements that the Habsburgs would take the Hungarian throne if Louis died without heirs.[28] However, other nobles turned to the nobleman Ioan Zápolya, who was being supported by Suleiman. Under Charles V and his brother Ferdinand I, the Habsburgs reoccupied Buda and took possession of Hungary. Reacting in 1529, Suleiman marched through the valley of the Danube and regained control of Buda; in the following autumn his forces laid siege to Vienna. This was to be the Ottoman Empire's most ambitious expedition and the apogee of its drive to the West. With a reinforced garrison of 16,000 men,[29] the Austrians inflicted the first defeat on Suleiman, sowing the seeds of a bitter Ottoman-Habsburg rivalry that lasted until the 20th century. His second attempt to conquer Vienna failed in 1532, as Ottoman forces were delayed by the siege of Güns and failed to reach Vienna. In both cases, the Ottoman army was plagued by bad weather, forcing them to leave behind essential siege equipment, and was hobbled by overstretched supply lines.[30]

By the 1540s a renewal of the conflict in Hungary presented Suleiman with the opportunity to avenge the defeat suffered at Vienna. In 1541 the Habsburgs attempted to lay siege to Buda but were repulsed, and more Habsburg fortresses were captured by the Ottomans in two consecutive campaigns in 1541 and 1544 as a result,[31] Ferdinand and Charles were forced to conclude a humiliating five-year treaty with Suleiman. Ferdinand renounced his claim to the Kingdom of Hungary and was forced to pay a fixed yearly sum to the Sultan for the Hungarian lands he continued to control. Of more symbolic importance, the treaty referred to Charles V not as 'Emperor' but as the 'King of Spain', leading Suleiman to identify as the true 'Caesar'.[32]"