Thirty Years' War
Fourthly, religious groups did not agree during the second half of the 16th century. The Peace of Augsburg did not work because some bishops had not given up their bishoprics, and Catholic rulers in Spain and Eastern Europe wanted to make Catholicism strong in the region, which caused fighting between the groups. The Catholics made many Protestants leave their homelands. Some places gave Protestants permission to worship. Those disagreements caused violence.