FREDERICK I. (1372?-144o), elector of Brandenburg, founder of the greatness of the House of Hohenzollern, was born at Nuremberg, a son of Frederick V., burgrave of Nuremberg, and first came into prominence by saving the life of Sigismund, king of Hungary, at the battle of Nicopolis in 1396. In 1397 he became burgrave of Nuremberg, and after his father's death in 1398 he shared Ansbach, Bayreuth, and the smaller possessions of the f am ily, with his only brother John, but became sole ruler after his brother's death in 1420. Loyal at first to King Wenceslaus, the king's neglect of Germany drove Frederick to take part in his deposition in 1400, and in the election of Rupert III., count pala tine of the Rhine, whom he accompanied to Italy in the following year. In 1401 he married Elizabeth, or Elsa, daughter of Fred erick, duke of Bavaria-Landshut (d. 1393), and in 1409 took ser vice again with King Sigismund, whom he assisted in his struggle with the Hungarian rebels. The double election to the German throne in 1410 first brought Frederick into relation with Branden burg. Sigismund, anxious to obtain another vote in the electoral college, appointed Frederick to exercise the Brandenburg vote on his behalf, and it was largely through his efforts that Sigismund was chosen German king. Frederick then restored a certain degree of order in Brandenburg, and was formally invested with the elec torate and margraviate by Sigismund at Constance on April 18, 1417 (see BRANDENBURG). He took part in the war against the Hussites, but became estranged from Sigismund when in the king invested Frederick of Wettin, margrave of Meissen, with the vacant electoral duchy of Saxe-Wittenberg. In 1427 he was one of the band of electors who sought to impose reforms upon Sigismund. An unsuccessful candidate for the German throne in 1438, Frederick was chosen king of Bohemia in 1440, but declined the honour. He took part in the election of Frederick III. as German king in 1440, and died at Kadolzburg on Sept. 21, of the same year. In 2902 a statue was erected to his memory at Friesack. Another one is in the "Siegesallee," Berlin.
See E. Brandenburg, Konig Sigmund and Kur f urst Friedrich I. von Brandenburg (1841).