The final failure of Christendom to preserve Eastern Europe from the infidel may be traced back to the disastrous Fourth Crusade[48] in the thirteenth century, when Venice, for purely selfish reasons, drove out the Greek rulers of Constantinople, and helped to establish a Latin or Frankish Empire. This Empire lasted for fifty-seven years, weak in its foundation, and growing ever weaker like a badly built house, ready to tumble to the ground at the first tempest. It pretended to embrace all the territory that had belonged to its predecessors, but many of the feudal landowners whom it appointed were never able to take possession of their estates that remained under independent Greek or Bulgarian princes, while in Asia Minor the exiled Greek emperors ruled at Nicea, awaiting an opportunity to cross the Bosporus and effect a triumphant return. Michael Paleologus, to whom the opportunity came, was an unscrupulous adventurer who, on account of his military reputation, had been appointed guardian of the young Emperor of Nicea, John Ducas, a boy of eight. Taking advantage of this position, Michael drove from the court all whom he knew to be disinterested partisans of his charge, and then declared himself joint emperor with the child. This ambitious claim was but a step to worse deeds, for before he was ten years old the unhappy little Emperor had been blinded and thrust into a dungeon by his co-emperor’s orders, and the Paleologi had become the reigning house of the Eastern Empire. [Sidenote: The Eastern Empire] This was an evil day for Christendom, for though Michael Paleologus beat down the resistance of all the Greek princes who dared to resent the way in which he had usurped the throne, and afterwards succeeded in entering Constantinople, yet neither he nor his descendants were the type of men to preserve what he had gained. Nearly all the Paleologi were weak and false: Michael himself so shifty in his dealings that his friends trusted him less than his enemies. Because he had won his throne by fraud and cruelty he was always suspicious, like Italian despots, lest one of his generals should turn against him and outwit him. Instead, therefore, of keeping his attention fixed on the steadily increasing power of the Mahometans, an inspection that would have warned a wise man to maintain a strong army along the borders of the Empire in Asia Minor, he was so afraid of his own Greek troops that, once established in Constantinople, he disbanded whole regiments, and exiled their best officers. Everything he did, in fact, was calculated merely to secure his immediate safety or advantage, with no thought for the future, so that he died leaving his kingdom an easy prey to foreign enemies strong enough to seize the advantage. [Illustration: The NEAR EAST in the MIDDLE AGES]