Peace of Passau
After the death of Martin Luther in 1546, the Schmalkaldic War started out as a conflict between two German Lutheran rulers in 1547. Soon, Holy Roman Imperial forces joined the battle and conquered the members of the Schmalkaldic League, oppressing and exiling many German Lutherans as they enforced the terms of the Augsburg Interim. Religious freedom in some areas was secured for Lutherans through the Peace of Passau in 1552, and under the legal principle of "Cuius regio, eius religio" (the religion of the ruler was to dictate the religion of those ruled) and the Declaratio Ferdinandei (limited religious tolerance) clauses of the Peace of Augsburg in 1555.