Petrograd: Academia, 1923. - 120 s. The Great Medieval Crusades , There are a number of political, economic, Religious and Cultural Change , In the West , In the East , which gave the world new demands and opened up unexpected prospects for humanity, Byzantium had to play the difficult and ungrateful role of a forced intermediary ,. which, receiving blows from the east from the ever-increasing Seljuk Turks, At the same time, it was put in mortal danger by the Western militias .. While for Western Europe the era of the Crusades was the beginning of a new era of its life, for Byzantium the same era marked the beginning of its decline and, as the crusader movements developed, revealed more and more clearly the fatal symptoms of the tragic death of the empire of the Greek Wasileans.