prevent the incorporation of the majority of the remaining Brothers of Dobjin, and of the lands and property given for their use he was able to save nothing but the castle of Dobjin.
Konrad now found himself in a very awkward position; he had introduced of his own will a foreign and hostile power which had all Western Europe and the Holy See to support it, which had unbounded means of discrediting the Poles and putting them in the wrong before the world; and these means the order never failed to use. In half a century after their coming the knights, by the aid of volunteers and contributions from all Europe, had converted Prussia, and considered Poland and the adjoining parts of Lithuania as sure conquests to be made at their own leisure and at the expense of all Western Christendom.
The first Polish territory acquired was Pomerania. The career of the knights was easy and successful till the union of Poland and Lithuania in 1386. In 1410, at the battle called by the names both of Grünwald and Tannenberg, the power of the order was broken. Some years later Pomerania was returned to Poland, and the order was allowed to remain in East Prussia in the position of a vassal to the Commonwealth. In this reduced state the knights lived for a time, tried to gain allies, but could not; the most they did—and that was the best for the German cause—was to induce Albert, a member of the Franconian branch of the Hohenzollerns, to become grand master. He began to reorganize the order, and tried to shake off allegiance to Poland; but finding no aid in the Empire or elsewhere, he acted on Luther's advice to introduce Protestantism and convert Prussia into a secular and hereditary duchy. This he did in 1525. Poland, with a simplicity quite equal to that of Konrad, who called in the order at first, permitted the change. The military monks married, and were converted into hereditary nobles. Albert became Duke of Prussia, and took the oath of allegiance to Poland. Later the Hohenzollerns of Brandenburg inherited the duchy, became feudatories of Poland as well as electors at home. This was the position during the war between Sweden and Poland described in The Deluge. Frederick William, known as the Great Elector, was ruling at that time in Brandenburg and Prussia. He acted with great adroitness and success; paying no attention to his oath as vassal, he took the part of one side, and then of the other
