At the same time the marquis of Montferrat, now the peaceable master of Thessalonica, undertook the conquest of Greece.[151] He advanced into Thessaly, passed the chain of mountains of Olympus and Ossa, and took possession of Larissa. Boniface and his knights, without fear and without danger, passed through the narrow straits of Thermopylæ, and penetrated into Bœotia and Attica. They put to flight Leo Sgurre, who was the scourge of a vast province; and their exploits might have reminded the Greeks of those heroes of the early ages who travelled about the world fighting monsters and subduing tyrants. As all the Greeks, for so long a time oppressed, sighed for a change, the heroes of the crusades were everywhere received as liberators. Whilst Boniface was becoming possessed of the beautiful countries of Greece, Geoffrey de Villehardouin, nephew of the marshal of Champagne, established the authority of the Latins in the Peloponnesus. After having driven the troops of Michael Comnenus to the mountains of Epirus, he occupied, without fighting, Coronea and Patras, and met with no resistance except in the canton of Lacedæmonia. The conquered lands and cities were given to the barons, who rendered fealty and homage to the king of Thessalonica and the emperor of Constantinople.[152] Greece then beheld lords of Argos and Corinth, grand sieurs of Thebes, dukes of Athens, and princes of Achaia. French knights dictated laws in the city of Agamemnon, in the city of Minerva,[153] in the country of Lycurgus, and in that of Epaminondas. Strange destiny of the warriors of this crusade, who had quitted the West to conquer the city and lands of Jesus Christ, and whom fortune had conducted into places filled with the remembrances of the gods of Homer and the glory of profane antiquity!
The Crusaders were not allowed to felicitate themselves long upon their conquests. Possessors of an empire much more difficult to be preserved than invaded, they had not the ability to master fortune, who soon took from them all that victory had bestowed. They exercised their power with violence, and conciliated neither their subjects nor their neighbours. Joannice, king of the Bulgarians, had sent an ambassador to Baldwin, with offers of friendship; Baldwin replied with much haughtiness, and threatened to compel Joannice to descend from his usurped throne. When despoiling the Greeks of their property, the Crusaders shut out from themselves every source of prosperity, and reduced men to whom they left nothing but life, to despair. To fill up the measure of their imprudence, they received into their armies the Greeks, whom they loaded with contempt, and who became their implacable enemies. Not content with reigning over cities, they were desirous of subjugating hearts to their will, and awakened fanaticism. Unjust persecutions exasperated the minds of the Greek priests, who declaimed with vehemence against tyranny, and who, reduced to misery, were listened to as oracles and revered as martyrs.