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.
Suleiman the Magnificent
While Sultan Suleiman was known as "the Magnificent" in the West, he was always "Kanuni" Suleiman or "The Lawgiver" () to his own Ottoman subjects. As the historian Lord Kinross notes, "Not only was he a great military campaigner, a man of the sword, as his father and great-grandfather had been before him. He differed from them in the extent to which he was also a man of the pen. He was a great legislator, standing out in the eyes of his people as a high-minded sovereign and a magnanimous exponent of justice". The overriding law of the empire was the Shari'ah, or Sacred Law, which as the divine law of Islam was outside of the Sultan's powers to change. Yet an area of distinct law known as the "Kanuns" (, canonical legislation) was dependent on Suleiman's will alone, covering areas such as criminal law, land tenure and taxation. He collected all the judgments that had been issued by the nine Ottoman Sultans who preceded him. After eliminating duplications and choosing between contradictory statements, he issued a single legal code, all the while being careful not to violate the basic laws of Islam. It was within this framework that Suleiman, supported by his Grand Mufti Ebussuud, sought to reform the legislation to adapt to a rapidly changing empire. When the Kanun laws attained their final form, the code of laws became known as the "kanun‐i Osmani" (), or the "Ottoman laws". Suleiman's legal code was to last more than three hundred years.