The most immediate result of this union was that Poland and Lithuania combined could renew their traditional struggle against the Teutonic Knights and fight it through to a successful conclusion. Not the least of the circumstances that contributed to their victory was the fact that, in the crisis of the conflict, the majority of the German nobles and cities of Prussia deserted the Knights and joined King Casimir, preferring the liberty which Poland could offer them to the tyrannous rule of the Teutonic Order. This was the second of those voluntary unions which form so striking and peculiar a feature of Polish history. By the peace of Thorn (1466), which ended this Hundred Years’ War, Danzig and West Prussia were incorporated in Poland, although with guarantees for a large measure of self-government, while East Prussia was left to the vanquished Knights to be held as a fief of Poland. Thus the mouth of the Vistula and a frontage upon the Baltic had been recovered and were to remain in Polish possession for the next three hundred years. Unfortunately for the peace of Europe, however, the Prussian question was not completely liquidated, as it might have been both in 1466 and on several later occasions. With a generosity or a lack of foresight which later historians have found it very hard to excuse, the Polish government in 1525 permitted the Teutonic Grand Master, Albert of Hohenzollern, to secularize East Prussia and turn it into a duchy hereditary in his family, though still a fief of Poland; and on the extinction of his line in 1618, Poland was induced to allow the transfer of the duchy to the Brandenburg branch of the family--the first great step towards the building up of that Hohenzollern monarchy which was to be the worst foe of Poland. Another most important result of the union of 1386 was the gradual fusion of Lithuania with Poland. History affords few stranger spectacles than this process by which the much larger and originally stronger state voluntarily submitted to being assimilated and absorbed by the smaller one. That result was due to the attractions which the more advanced civilization of Poland possessed for the upper classes in the Lithuanian realm; to the desire of the Lithuanian noblesse to secure the liberties and privileges of the Polish nobles; and to the remarkable tact, cleverness, and perseverance with which for centuries the Poles pursued the aim of binding their somewhat wayward neighbor irrevocably to their side. The union between the two states, originally based solely on the person of the common ruler, was steadily strengthened until by the agreement of 1569 it was turned into a permanent organic union--a partnership which was to last through good days and through evil until the Partitions.