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.
Haseki sultan
The title was first used in the 16th century for Hürrem Sultan, also known as Roxelana, when she was given favor by Suleiman the Magnificent. She was his chief consort and the mother of Selim II. Hürrem Sultan was married to Sultan Suleiman, becoming both his legal wife and one of the most powerful women in the Ottoman Empire. The title was next held by Nurbanu Sultan, favourite wife of Selim II, and the mother of the next Sultan Murad III. In 1575, just after Murad's accession, Safiye Sultan became the haseki and was given a higher rank than the sultan's own sisters, Ismihan Sultan, Gevherhan Sultan and Şah Sultan, and his aunt Mihrimah Sultan.