Suleyman I (1494-1566), a sultan of the Ottoman Empire (1520-1566). During his reign the empire reached its zenith of power and splendour. In 1521, at the beginning of his reign, Suleyman captured the city of Belgrade (now in Serbia). The following year he repelled the Knights of Saint John of Jerusalem, a military and religious order, from the Island of Rhodes in the Aegean Sea. In 1526 he again invaded Hungary, killing Louis II, King of Hungary. Suleyman next directed his arms against Iran. In 1534 he conquered the cities of Tabraz and Baghdad. In 1535 he concluded an alliance with Francis I, King of France, against Holy Roman Emperor Charles V. Suleyman is considered the greatest of Ottoman sultans. He excelled as an administrator, earning the title Kanuni and was an influential patron of the arts and sciences. At his death the Ottoman Empire controlled much of the Balkans, Northern Africa, and the Middle East, and was the ruling power on the Mediterranean Sea.