Frederick lived in close friendship with the emperor Charles IV., who formally invested him with Ansbach and Bayreuth and made him a prince of the empire in 1363. In spite of the troubled times in which he lived, Frederick was a successful ruler, and introduced a regular system of public finance into his lands. In 1397 he divided his territories between his sons John and Frederick, and died in the following year. His elder son, John III., who had married Margaret, a daughter of the emperor Charles IV., was frequently in the company of his brothers-in-law, the German kings Wenceslaus and Sigismund. He died without sons in 1420. Since 1397 the office of burgrave of Nuremberg had been held by John's brother, Frederick, who in 1415 received Brandenburg from King Sigismund, and became margrave of Brandenburg as Frederick I. (q.v.). On his brother's death in 1420 he reunited the lands of his branch of the family, but in 1427 he sold his rights as burgrave to the town of Nuremberg. The subsequent history of this branch of the Hohenzollerns is identified with that of Brandenburg from 1415 to 1701, and with that of Prussia since the latter date, as in this year the elector Frederick III. became king of Prussia. In 1871 William, the seventh king, took the title of German emperor. While the electorate of Brandenburg passed according to the rule of primogeniture, the Franconian possessions of the Hohenzollerns, Ansbach and Bayreuth, were given as appanages to younger sons, an arrangement which was confirmed by the _dispositio Achillea_ of 1473. These principalities were ruled by the sons and descendants of the elector Albert Achilles from 1486 to 1603; and, after reverting to the elector of Brandenburg, by the descendants of the elector John George from 1603 to 1791. In 1791 Prince Charles Alexander (d. 1806), who had inherited both districts, sold his lands to Prussia.