RESERVATUM ECCLESIASTICUM. - Name given to one of the most important clauses of the Peace of Augsburg (Sept. 25, 1555) between the Protestants and the Catholics of Germany.
After the second war, known as the Schmalkaldic War, closed by the Truce of Passau (1552), the Lutherans, feeling themselves the stronger, wanted to impose their conditions; the Emperor Charles V delegated to his brother, King Ferdinand, full powers to negotiate the peace. The Diet of Augsburg opened on Feb. 5, 1555, and the negotiations were laborious; the Lutherans, having previously assembled at Naumburg, had committed themselves to making no concession whatsoever regarding the Augsburg Confession (Lutheran). Ferdinand and the majority of the Catholic princes, unprepared to continue the war, were resolved to make peace at any cost, despite the contrary opinion of the pontifical nuncios. The Lutheran princes therefore obtained what they wanted: the ius reformandi and the ius in sacra, that is, the right to impose the Augsburg confession upon their subjects (thus excluding Calvinism and every other Protestant denomination) and to be completely withdrawn from episcopal jurisdiction. Moreover, all the "secularizations," that is, the goods of the Church usurped by them, up to the year 1552, passed definitively into their domain. Subsequent "secularizations" were declared invalid, but the bishops and abbots, who were direct members of the Empire, could pass over to Lutheranism, losing all their rights over their bishoprics or abbeys by r. e.; to this clause was given the name of r. e.
The official text of the Treaty expressed itself thus: "Since the members of the Empire of the two religions have not been able to reach agreement on the manner of regulating the matter of ecclesiastics who abjure the ancient religion, the king [Ferdinand] declares, by virtue of the full powers that the Emperor has conferred upon him, that any archbishop, bishop, prelate and other member of the Catholic clergy, disposed to change religion, will by that very fact lose his office, dignity and revenues, without prejudice to his honors. To the Chapters, to persons having the capacity, by tradition and rights, to make ecclesiastical appointments, will be left every freedom to elect a person of the ancient religion in place of the one who has resigned" (Lehmann, op. cit. in bibl., pp. 51-52).
Since in the text of the Treaty it was asserted that "agreement had not been able to be reached" and that the r. e. was nothing but a decree of the King, in the name of the Emperor, the Protestants agreed among themselves not to consider it binding upon them. There followed, from 1582 onward, the so-called War of Cologne, concerning the elector-archbishop of that city, who wished to "secularize" himself while retaining his office. The violations of the r. e. on the part of the Lutherans were so numerous that they became one of the most serious causes of the Thirty Years' War (1618-48).