The Ottoman Turks first appeared in history in 1227 as a group of several thousand persons fleeing from Central Asia before the advance of Mongol invaders. Just 226 years later an Ottoman army--90,000 warriors--stood at the gates of Constantinople, capital of Byzantium, the successor to the legendary Roman Empire. The transformation of the Ottoman Turks from a refugee horde to a mighty military force was a testament to the remarkable leadership of the Ottomans in that period and to their highly effective governance structure.

For decades the advance of Ottoman strength and the enlargement of its territory had seemed inexorable to the Byzantines and to other interested observers such as the Venetians. In 1438 John VIII Palaeologus, the Byzantine emperor, with a huge entourage had made a personal visit to Venice and elsewhere in Italy in a desperate effort to assemble allies against the Ottomans. Much was said and little was achieved.

In fact, the Venetians had succeeded better than most western powers at establishing and maintaining--subject to intermittent interruptions--important trading relationships with the Ottomans as Ottoman power and territory grew. Nonetheless, in early 1453 as the Ottoman siege on Constantinople tightened, only the Venetians attempted to provide any substantial military assistance to the Byzantines.

All defense was futile, however. The city fell on May 29, 1453. Henceforth, all Venetian outposts in the eastern Mediterranean were at risk.

For Europe as a whole, the great unanswered question was: how far west would the Ottoman expansion ultimately reach? By 1529 the Ottoman army was at the gates of Vienna, the geographic center of Europe. That unsuccessful siege was repeated in 1681, provoking at last a unified response from the major powers of Western Europe. The Ottoman advance into Europe had been stemmed at last.