Peace of Passau
The 1552 Peace of Passau ended the Schmalkaldic War between Protestants and Catholics in the Holy Roman Empire, while the 1555 Peace of Augsburg tried to prevent future conflict by fixing existing boundaries. Under the principle of "cuius regio, eius religio", states were either Lutheran, then the most usual form of Protestantism, or Catholic, based on the religion of their ruler. Other provisions protected substantial religious minorities in cities like Donauwörth and confirmed Lutheran ownership of property taken from the Catholic Church since Passau.