first permanent legal basis for the existence of Lutheranism as well as Catholicism in Germany, promulgated on September 25, 1555, by the Diet of the Holy Roman Empire assembled earlier that year at Augsburg.

The emperor Charles V's provisional ruling on the religious question, the Augsburg Interim of 1548, had been overthrown in 1552 by the revolt of the Protestant elector Maurice of Saxony and his allies. In the ensuing negotiations at Passau (summer 1552), even the Catholic princes had called for a lasting peace, for fear that otherwise the religious controversy would never be settled. The emperor, however, was unwilling to recognize the religious division in Western Christendom as permanent and granted a peace only until the next imperial Diet.

The Diet, which opened at Augsburg on February 5, 1555, was proclaimed by Charles V, but, not wishing to take part in the inevitable religious compromises, he refused to attend the proceedings and empowered his brother Ferdinand (the future emperor Ferdinand I) to settle all questions.

The Diet determined that in the future no ruler in the empire should make war against another on religious grounds and that this peace should remain operative until the churches were peacefully reunited. Only two churches were recognized, the Roman Catholic and the adherents of the Augsburg Confession—i.e., the Lutherans. Moreover, in each territory of the empire, only one church was to be recognized, the religion of the ruler's choice being thus made obligatory for his subjects. Any who adhered to the other church could sell his property and migrate to a territory where that denomination was recognized. The free imperial cities, which had lost their religious homogeneity a few years earlier, were exceptions to the general ruling. Lutheran and Catholic citizens in these cities remained free to exercise their religion as they pleased. The same freedom was furthermore extended to Lutheran knights and to towns and other communities that had for some time been practicing their religion in the lands of ecclesiastical princes of the empire. This last concession provoked vehement Catholic opposition, and Ferdinand circumvented the difficulty by deciding the matter on his own authority and including the clause in a separate article.

Ecclesiastical lands taken by Lutheran rulers from Catholic prelates who were not immediate vassals of the emperor were to remain with the Lutherans if continuous possession could be proved from the time of the Treaty of Passau (August 2, 1552), but, to ensure the permanence of the remaining ecclesiastical territories, the Catholics gained the condition that in the future any ecclesiastical prince who became Protestant should renounce his office, lands, and revenues. Because the Lutherans would not accept this ecclesiastical reservation and the Catholics would not yield, Ferdinand incorporated the clause on his own authority with a note that agreement had not been reached on it. In fact, Lutherans were in many cases able to nullify its effect.

The wish for a lasting settlement was so strong that the compromise peace, which satisfied no one completely and had many loopholes, was accepted. In spite of its shortcomings, the Peace of Augsburg saved the empire from serious internal conflicts for more than 50 years. It also strengthened the power of the territorial ruler. Germany thus emerged from the 16th century as a religiously divided country.