Margraviate of Brandenburg fief of the Polish–Lithuanian Commonwealth, to which the electors paid homage. The electors of Brandenburg spent the next two centuries attempting to gain lands to unite their separate territories (the Mark Brandenburg, the territories in the Rhineland and Westphalia, and Ducal Prussia) to form one geographically contiguous domain. In the Peace of Westphalia ending the Thirty Years' War in 1648, Brandenburg-Prussia acquired Farther Pomerania and made it the Province of Pomerania by the Treaty of Stettin (1653). In the second half of the 17th century, Frederick William, the "Great Elector", developed Brandenburg-Prussia into a major power. The state constructed Brandenburg's
Treaty of Mutual Cooperation and Security Between the United States and Japan To support that requirement, it provided for the continued presence of US military bases in Japan. The treaty also included general provisions on the further development of international cooperation and on improved future economic cooperation. The treaty has lasted longer than any other alliance between two great powers since the 1648 Peace of Westphalia. The treaty had a minimum term of 10 years. However, it provided that it would remain in force permanently unless one party gives one year's notice that it wishes to terminate it. The earlier Security Treaty of 1951 provided the initial basis for the Japan's security