The Ottoman Turks, or "Osmanli," were originally merely one of the many Turkish hordes which entered Asia Minor after the downfall of Byzantine rule. They owed their greatness mainly to a long line of able sultans, who gradually absorbed the neighbouring Turkish tribes and used this consolidated strength for ambitious conquests both to east and west. In 1453 the Osmanli extinguished the old Byzantine Empire by taking Constantinople, and within a century thereafter they had conquered the Moslem East from Persia to Morocco, had subjugated the whole Balkan Peninsula, and had advanced through Hungary to the walls of Vienna. Unlike their Mongol cousins, the Ottoman Turks built up a durable empire. It was a barbarous sort of empire, for the Turks understood very little about culture. The only things they could appreciate were military improvements. These, however, they thoroughly appreciated and kept fully abreast of the times. In their palmy days the Turks had the best artillery and the steadiest infantry in the world, and were the terror of Europe. Meantime Europe was awakening to true progress and higher civilization. While the Moslem East was sinking under Mongol harryings and Turkish militarism, the Christian West was thrilling to the Renaissance and the discoveries of America and the water route to India. The effect of these discoveries simply cannot be over-estimated. When Columbus and Vasco da Gama made their memorable voyages at the end of the fifteenth century, Western civilization was pent up closely within the restricted bounds of west-central Europe, and was waging a defensive and none-too-hopeful struggle with the forces of Turanian barbarism. Russia lay under the heel of the Mongol Tartars, while the Turks, then in the full flush of their martial vigour, were marching triumphantly up from the south-east and threatening Europe's very heart. So strong were these Turanian barbarians, with Asia, North Africa, and eastern Europe in their grasp, that Western civilization was hard put to it to hold its own. Western civilization was, in fact, fighting with its back to the wall--the wall of a boundless ocean. We can hardly conceive how our mediaeval forefathers viewed the ocean. To them it was a numbing, constricting presence; the abode of darkness and horror. No wonder mediaeval Europe was static, since it faced on ruthless, aggressive Asia, and backed on nowhere. Then, in the twinkling of an eye, the sea-wall became a highway, and dead-end Europe became mistress of the ocean--and thereby mistress of the world.