The son of Sultan Murad II (reigned 1421-1451), Mohammed II assumed full sovereignty on his father's death in February 1451. His predecessors had conquered much of the southern Balkans and had subjected the bulk of Asia Minor as well; but the continued independence of Constantinople and of other Greek territories both prolonged the life of the faded Byzantine Empire and deprived the new Turkish power of its logical capital while also posing the danger of some Christian counteroffensive from this strategic center. The ambitious young sultan therefore was determined that the final conquest of Constantinople should be his first major achievement, and he launched his great siege of this city in early April 1453.

Despite heroic resistance under the last Byzantine emperor, Constantine XI, Constantinople was taken by storm on May 29. Mohammed II quickly restored the city's splendor and prosperity, making it the capital of an imperial Turkish regime whose coherent scale and systematic scope were the results of his own massive reorganization. In 1460 Mohammed completed the annexation of the Byzantine Peloponnesus, and in the following year he conquered the truncated empire of Trebizond, thus eliminating the last remnants of independent Greek authority.

Meanwhile, Mohammed expanded Turkish power in the Balkans. He carried out the final annexation of Serbia by 1459. His siege of Belgrade was foiled, however, in 1456 by the Hungarian hero John Hunyadi. The Hungarians further attempted, with only minimal success, to prevent the Turkish conquest of Bosnia and Herzigovina. Mohammed also subdued Walachia. He was unable to conquer Moldavia; but in 1475 he seized Caffa, Tana, and Azov, securing control of the Crimea and the northern Black Sea areas. In Albania, Mohammed carried on the struggle his father had launched; only in the late 1470s was he able to occupy the key fortresses of Albania.

Alone and isolated, however, the sturdy Montenegrins resisted Turkish conquest.

 

Mohammed, more than any other sultan, made good the Turkish domination of Asia Minor. During the 1460s he conquered the long-independent emirate of Karaman. When Uzun Hasan, the Turkoman ruler, attempted to challenge Mohammed in eastern Asia Minor, the Sultan defeated him in the decisive battle of Otluk-beli near Terdshan on the upper Euphrates in 1472. The victory guaranteed Mohammed's Asiatic power and freed him for further conquests in Europe.

To the West, Mohammed was a source of anguish and terror. Stung by his capture of Constantinople, successive popes talked of crusades against the Turk and exhorted the European powers to join the common cause. Although such plans foundered, Mohammed faced a strong Western foe in Venice which found Turkish disruption of its Levantine commerce intolerable. From 1463 to 1479 Venice made war on Mohammed, supporting the Albanians and the Turkomans against him and attacking his coasts. But in 1470 the Venetians lost Negroponte (Euboea), and a few years later Mohammed's forces, victorious in Albania, menaced Venice itself around the Adriatic headlands. The republic was therefore forced to accept disadvantageous peace terms. On the other hand, when Mohammed attempted to seize the island of Rhodes in 1480, it was successfully defended by the knights of St. John (Hospitalers).

But Mohammed's most daring stroke was also executed in 1480. Taking advantage of Italy's internal disorganization, he sent a fleet to the peninsula's southern shores. In August it seized Otranto and held it for a month. The panic-stricken Italian powers saw this act as the prelude to a serious effort by the Sultan, who had boasted that he would match his conquest of the "new Rome" (Constantinople) by taking the old one. But the alarm was groundless: during the following year, as he prepared a new expedition against Rhodes, Mohammed suddenly fell ill and died on May 3, 1481, leaving his empire to a period of slackness and division under his weak son and successor, Bayazid II (reigned 1481-1512).