Peace of Augsburg
The Peace of Augsburg, also called the Augsburg Settlement, was a treaty between Charles V, Holy Roman Emperor, and the Schmalkaldic League, signed in September 1555 at the imperial city of Augsburg. It officially ended the religious struggle between the two groups and made the legal division of Christianity permanent within the Holy Roman Empire, allowing rulers to choose either Lutheranism or Roman Catholicism as the official confession of their state. However, the Peace of Augsburg arrangement is also credited with ending much Christian unity around Europe. Calvinism was not allowed until the Peace of Westphalia.