Thanks to these fortresses, the Greeks succeeded in repulsing the Turkish assaults, so vehemently renewed in 1177, until, by the Latin conquest of 1204, the Byzantine Empire was entirely restricted to Asia Minor, where, in the so-called Nicæan Empire, it experienced such a promising rebirth that it soon embraced the whole northern half of western Asia Minor. This new kingdom secured to the Greeks the mastery in Asia Minor for 125 years more, and it would have secured it to them for an even longer period if the Mongol invasion of 1241 and the consequent weakening of the Seljuks had not tempted the ambitious Greek emperors to stretch out their hands once more toward that fatal Constantinople, instead of using their whole strength in maintaining their hold on Asia Minor; for the Greek Empire of that time was no longer strong enough to hold control over two continents that were so seriously threatened, especially since a new avalanche was already rolling in from the east, the mighty Ottomans, who rose up in the strength of youth among the ruins of the fallen empire of the Seljuks. What the Seljuks in 240 years had failed to accomplish, the Ottomans were destined to bring about in a single generation, the ruination of Hellenism in Asia Minor. It was in 1299 that the petty Turkish feudal prince, Osman, broke through the fortified region of the Sangarios, and after sixteen years of desperate fighting succeeded in forcing his way through to Nicæa, the chief defensive point of the Greeks, in order to lay the foundations of that great Ottoman Empire that was to be the mighty successor to the Byzantine Empire. He still met with almost invincible resistance; Nicæa with its mighty walls could not be forced, and it was only in 1326, the year of his death, that Prusa, after a ten-year siege, fell, and under the name of Brussa became the first Ottoman capital. In 1330, and after a siege of fifteen years, came the fall of Nicæa, and later that of Nicomedia. The hardest part of the task had thus been done, the first great breach had been made in the stronghold of the Greek Empire, and the conquerors now turned to the south. Pergamon fell in 1335, Sardis in 1369, and Philadelphia (Alashehr), the last of the Greek cities of the interior, which, according to the expression of a Greek chronicler, stands like a star in a clouded sky, was captured in 1391. Smyrna, the old Greek acropolis, had already fallen a prey early in the 14th century to the Seljuks, who had found in Aïdin, the ancient Tralles, a last support for their sinking power. Apart from Trebizond in the extreme northeast, which up to 1461 maintained itself as the capital of the little coast state which was also called Trebizond, all Asia Minor was now in the hands of the Turks. The Greeks, as a political factor, had ceased to play any part. The question as to whether they had ceased to be of any importance as a civilizing and cultural factor we must now attempt to investigate.