John Frederick I definition of John Frederick I in the Free Online Encyclopedia.

John Frederick I, 1503–54, elector (1532–47) and duke (1547–54) of Saxony; last elector of the Ernestine branch of the house of Wettin Wettin (vĕt`ĭn), German dynasty, which ruled in Saxony, Thuringia, Poland, Great Britain, Belgium, and Bulgaria.
..... Click the link for more information. . Like his father, John the Steadfast, whom he succeeded, John Frederick was a devout Lutheran. A leader of the Schmalkaldic League Schmalkaldic League (shmälkäl`dĭk), alliance formed in 1531 at Schmalkalden by Protestant princes and delegates of free cities.
..... Click the link for more information. , he vacillated in loyalty to Holy Roman Emperor Charles V Charles V, 1500–1558, Holy Roman emperor (1519–58) and, as Charles I, king of Spain (1516–56); son of Philip I and Joanna of Castile, grandson of Ferdinand II of Aragón, Isabella of Castile, Holy Roman Emperor Maximilian I, and Mary of
..... Click the link for more information. , but he was thrown into opposition when Charles undertook the Schmalkaldic War to crush the independence of the imperial states in Germany and to restore Christian unity. Captured (1547) in the battle of Mühlberg, John Frederick was forced to renounce the electorate in favor of his cousin and enemy, Maurice Maurice, 1521–53, duke (1541–47) and elector (1547–53) of Saxony. A member of the Albertine branch of the ruling house of Saxony, he became duke of Albertine Saxony during the Protestant Reformation.
..... Click the link for more information. , duke of Saxony. He retained only a remnant of his lands and the title of duke. He refused to abandon his religious beliefs during subsequent imprisonment (1547–52).