colonies--supreme among them the magnificent city of Danzig, the Venice of the Baltic, the great seaport of the Slavic countries, with its rich St. Mary's Church and the palaces of its merchant princes; and beyond it on another arm of the Vistula, its modest rival, Elbing: farther up, the stately towers and broad avenues of Marienburg; near it the great princely castle of the Teutonic order, the most beautiful architectural monument of Northern Germany; and in the Vistula valley, on a rich alluvial soil, the old prosperous colonial estates: one of the most productive countries of the world, protected against the devastations of the Slavic stream by massive dikes dating back to the days of the Knights. Still farther up were Marienwerder, Graudenz, Kulm, and in the low lands of the Netze, Bromberg, the centre of the German border colonies among a Polish population. Smaller German towns and village communities were scattered through the whole territory, and the rich Cistercian monasteries of Oliva and Peplin had been zealous colonizers. But in the fifteenth century the tyrannical severity of the Teutonic order had driven the German cities and landowners of West Prussia to an alliance with Poland. The Reformation of the sixteenth century won the submission not only of the German colonists but of three-quarters of the nobility in the great republic of Poland; and toward 1590 about seventy out of a hundred parishes in the Slavic district of Pomerelia were Protestant. It seemed for a short time as if a new commonwealth and a new culture were about to develop in the Slavic East--a great Polish State with German elements in the cities. But the introduction of the Jesuits brought an unsalutary change. The Polish nobility returned to the Catholic Church: in the Jesuit schools their sons were trained to proselytizing fanaticism, and from that time on the Polish State declined, conditions becoming worse and worse.