The Duke of Saxony was one of the seven Electors. When Charles V became Emperor in 1519, the Duke of Saxony was Frederik III (or Frederick III), also known as Frederik the Wise. He was a Protestant and Martin Luther was living in Wittenberg under Frederik’s protection.

When Charles V decided to eliminate the Protestant religion from the Holy Roman Empire, he waged war on electoral Saxony. The Elector then was John the Constant. He joined forces with Philip of Hess against the Emperor.

In 1532, John died and the new elector, John-Frederik I, was beaten by Charles V at the Battle of Mühlberg. John-Frederik was forced to sign the Wittenberg Capitulation which gave the electorate to another Saxony prince, Maurice. The Emperor also gave some of the lands belonging to John-Frederik to Maurice.

Unfortunately for Charles V, Maurice was also a Protestant and joined up with other Protestant princes to fight the Emperor. This time the Protestants were victorious, and the Emperor was compelled to put his signature to "The Peace of Augsburg" which allowed the Protestant states to remain Protestant.