The Byzantine Empire lasted for 1123 years, a period longer than that which separates us from William the Conqueror. The third and final volume of the author's history of Byzantium, this book tells of the dire consequences of the defeat of the Seljuk Turks at the battle of Manzikert in 1071; of the Fourth Crusade, whose Crusaders, led by the octogenarian Doge of Venice, turned their attention away from the holy places to hurl themselves against Constantinople, sacking the city and setting up a succession of Frankish thugs on the imperial throne; and of the 200-year struggle by the restored Empire against the inexorable advance of the Ottoman Turks. This account of the city's fall, the last great epic in the history of the Middle Ages, is the climax of the story. The Byzantines, under their last Emperor, Constantine XI, heroically held out against the immense army of the Sultan Mehmet II for 55 days until, in 1453, the massive walls of Constantinople crumbled at last.