A league of Lutheran princes formed to protect their religious interests. In 1525 the Roman Catholic princes had come together to form the League of Dessau. Early in the following year Elector John the Constant of Saxony and Landgravemade an alliance, which other princes joined. After the Diet of Augsburg the formal organization of the took place (December 1530). It was purely a defensive league. Strasbourg, Ulm, Constance, Reutlingen, and other cities joined in. In 1535, at the Diet of Smalcald, it was agreed that new members would have “to provide for such teaching and preaching as was in harmony with the Word of God and the pure teaching of our [Augsburg] Confession.” of England found this stipulation one barrier, which prevented him from joining the League in 1536 and 1538. Attempts to reconcile the Lutherans and Roman Catholics failed at Ratisbon in 1541. In 1546, at the meeting with the emperor, no agreement was reached. The Smalcald War culminated in the defeat of the Smalcald League in the battle of Muehlberg and the Wittenberg Capitulation (1547). Mortiz of Saxony joined the emperor-for which he received the electorate-and thus insured the defeat of the Smalcald League. In the * (1555), by the principle cuius regio, eius religio the Lutheran princes secured the right to regulate the religious affairs of their territories.