Classical Age of the Ottoman Empire
Expansion continued during the first half of the reign of Suleiman I (r. 1520-1566), who conquered first Belgrade (1521) and Rhodes, before invading Hungary in 1526, defeating and killing King Louis II in the Battle of Mohács and briefly occupying Buda. Lacking a king, Hungary descended into civil war over the succession, and the Ottomans gave support to John Zápolya as a vassal prince. When their rivals the Habsburgs began to achieve the upper hand, Suleiman directly intervened by again conquering Buda and annexing it to the empire in 1541. Elsewhere, Suleiman led major campaigns against Safavid Iran, conquering Baghdad in 1534 and annexing Iraq. Ottoman rule was further extended with the incorporation of much of North Africa, the conquest of coastal Yemen in 1538, and the subsequent annexation of the interior.
Mahidevran
When Selim I died in 1520, Suleiman moved to Constantinople, the capital of the Ottoman Empire, along with his family to ascend the throne. In 1521, Suleiman lost his two other sons, nine-year-old Mahmud and the toddler Murad, Mustafa became the eldest of his princely generation.
Mahidevran became Suleiman's Baş Kadın (a rank equivalent to main consort before the invention of the royal title Haseki Sultan for Hürrem Sultan). In the Istanbul harem, Mahidevran had a very influential rival, Hürrem Sultan (also known as Roxelana in Europe), who soon proved to be Suleiman's favourite.