Geoffroy’s brother and successor, the warlike Guillaume de Villehardouin, saw the Frank state in the Morea reach its zenith, and by his rashness contributed to its decline. Born in Greece, and speaking Greek, as the _Chronicle of the Morea_ expressly tells us, the third of the Villehardouins began by completing the conquest of what was his native land. It was he who laid siege to the rock of Monemvasia for three long years, till at last, when the garrison had been reduced to eat mice and cats, the three _archontes_ advanced along the narrow causeway which gives the place its name[51], and surrendered on terms which the prince wisely granted. It was he, too, who built the noble castle of Mistra on the site of the Homeric Messe, now abandoned to tortoises and sheep, but for two centuries a great name in the history of Greece. To a ruler so vigorous and so determined even the weird Tzakones, that strange tribe, perhaps Slavs but far more probably Dorians, which still lingers on and cherishes its curious language around Leonidi, yielded obedience; while the men of Maina, hemmed in by two new castles, ceased to trouble. For the first and last time in its history the whole Peloponnese owned the sway of a Frank prince, except where, at Modon and Koron, Venice kept “its right eye,” as it called those places, fixed on the East. So powerful a sovereign as St Louis of France wished that he had some of Guillaume’s knights to aid him in his Egyptian war; and from seven hundred to one thousand horsemen always attended the chivalrous Prince of Achaia. His court at La Crémonie, the French version of Lacedæmonia, was “more brilliant than that of many a king”; and this brilliance was not merely on the surface. “Merchants,” says Sanudo, “went up and down without money, and lodged in the house of the bailies; and on their simple note of hand people gave them money[52].” But Guillaume’s ambition and his love of fighting for fighting’s sake involved the principality in disaster. Not content with beginning the first fratricidal war between the Frank rulers of the East by attacking Guy de la Roche, Lord of Athens, he espoused the cause of his father-in-law, the Greek Despot of Epeiros, then engaged in another brotherly struggle with the Greek Emperor of Nice. On the field of Pelagonia in Macedonia the Franks were routed; and the Prince of Achaia, easily recognised by his prominent teeth, was dragged from under a heap of straw, where he was lying, and carried off a prisoner to the court of the Emperor Michael VIII.