Religious tensions remained strong throughout the second half of the 16th century. The Peace of Augsburg began to unravel as some bishops converting to Protestantism refused to give up their bishoprics. This was evident from the Cologne War (1582–83), a conflict initiated when the prince-archbishop of the city converted to Calvinism. Religious tensions also broke into violence in the German free city of Donauwörth in 1606, when the Lutheran majority barred the Catholic residents from holding a procession, provoking a riot. This prompted intervention by Duke Maximilian of Bavaria on behalf of the Catholics.