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.
Sultan of Egypt
From 1882 onwards, Egypt's status became deeply convoluted: officially a province of the Ottoman Empire, semi-officially a virtually independent state with its own monarchy, armed forces, and territorial possessions in Sudan, and for practical purposes a British puppet. The legal fiction of Ottoman sovereignty in Egypt was finally ended in 1914 when the Ottoman Empire joined the Central Powers in First World War. Alarmed that the anti-British Khedive Abbas II would side with the Ottomans, the British deposed him in favor of his uncle Hussein Kamel and declared Egypt a British protectorate. Symbolizing the official end of Ottoman rule, Hussein Kamel took the title Sultan as did his brother Fuad I who succeeded him in 1917, though in reality Egypt remained under British domination. Both Hussein Kamel and Fuad maintained Egypt's claim to Sudan, with Egyptian nationalists declaring both in turn to be the "Sultan of Egypt and Sudan".