Transformation of the Ottoman Empire
Sultan Suleiman I (r. 1520–1566) was the longest-reigning sultan in Ottoman history, but the last years of his reign were characterized by uncertainty over who would be his successor. Suleiman had three sons who could hope to succeed, Mustafa, Bayezid, and Selim. While the latter two were the children of Suleiman's wife Hurrem Sultan, the first was the son of an earlier concubine. Mustafa may have felt that his half-brothers possessed an unfair advantage over him, and thus worked to secure the favor of the military. Perhaps suspecting that Mustafa planned to dethrone him just as his own father had done to his grandfather, Suleiman acted first and in 1553 ordered that Mustafa be executed. The death of Hurrem Sultan in 1558 triggered open conflict between the two remaining candidates, and Selim ultimately emerged victorious. Suleiman further strengthened his son's position by arranging a marriage between Selim's daughter and the influential Sokollu Mehmed Pasha (Grand Vizier 1565–1579). Suleiman died in 1566, while besieging the fortress of Szigetvar in Hungary, bringing Selim to the throne.
Selim I
Selim's conquest of the Middle Eastern heartlands of the Muslim world, and particularly his assumption of the role of guardian of the pilgrimage routes to Mecca and Medina, established the Ottoman Empire as the most prestigious of all Sunni Muslim states. His conquests dramatically shifted the empire's geographical and cultural center of gravity away from the Balkans and toward the Middle East. By the eighteenth century, Selim's conquest of the Mamluk Sultanate had come to be romanticized as the moment when the Ottomans seized leadership over the rest of the Muslim world, and consequently Selim is popularly remembered as the first legitimate Ottoman Caliph, although stories of an official transfer of the caliphal office from the Abbasids to the Ottomans were a later invention.