A few years earlier, a certain Othman, a Turk, had become the vassal of the Seljukian Sultan, and had been granted a district of the Phrygian highlands, on the very borders of the Greek Empire, on condition that he would take up arms against the Greeks. Not many years passed before Othman, through the death of the last Sultan of the Seljuk line, had stepped into his place as an independent prince and the future founder of the Ottoman Empire. He outlived Michael Palæologus and his successor, and managed before his death to push the frontiers of the Turkish Empire forward to the Sea of Marmora. His son Orkhan completed the conquest of Bithynia--a {267} comparatively easy task now that the mistaken policy of the Greek Emperors had turned the troops of "hardy mountaineers into a trembling crowd of peasants without spirit or discipline." By the year 1333, nothing remained of the Greek Empire in Asia but the town of Chalcedon and the strip of land that faced Constantinople across the straits. The rule of the Ottoman Turks over their newly-conquered territory was firm and just enough, and was strengthened by material drawn from the ranks of the vanquished inhabitants. One of their demands was that a yearly tribute of young boys should be paid to them by the Christians. At first a terrible rumour spread that these children were killed and eaten by the infidels. But what really happened was that these boys were trained very carefully as soldiers, and became the "Janissaries," or "New Soldiers" of the Ottoman army, against whom nothing could stand. They were forced, of course, to become followers of Islam, and they were appointed to all the highest offices of state. But their chief energy was reserved for the attacks made upon the land of their origin. Gradually the Ottoman Turks crept nearer and nearer the heart of the Eastern Empire. A certain crafty Prime Minister of Constantinople, John Cantacugenus, in his determination to supplant his young sovereign, a child of nine, actually called in their aid and allowed them to over-run Thrace. By the time that the usurper had won his way as joint ruler with his master, to the imperial throne, all that remained of the coveted empire was Constantinople, the towns of Adrianople and Thessalonica, and the {268} Byzantine province in the Peloponnesus. His fatal alliance with the Turks had been cemented by a marriage between the Sultan Orkhan and his daughter Theodora; and when John Palæologus, the rightful sovereign, refused to submit to this arrangement of twin rulers, Cantacugenus at once called in his son-in-law to his help. Once more the Ottomans swarmed into Thrace, and, though they found that Cantacugenus had been deposed and forced to become a monk, they were not disposed to retreat without some substantial indemnity. They seized upon and settled in a province of Thrace, and within two years had the whole district, together with the city of Adrianople, in their hands.