As the conflict had by this time resolved itself into a duel between him and Charles, the emperor was now at last able to put through, at the Diet of Augsburg, a settlement of the religious question.
[Sidenote: Religious Peace of Augsburg, September 25, 1555] The principles of the Religious Peace were as follows: (1) A truce between states recognizing the Augsburg Confession and Catholic states until union was possible.

All other confessions were to be barred--a provision aimed chiefly at Calvinists.
(2) The princes and governments of the Free Cities were to be allowed to choose between the Roman and the Lutheran faith, but their subjects must either conform to this faith--on the maxim famous as _cujus regio ejus religio_--or emigrate.

In Imperial Free Cities, however, it was specially provided that Catholic minorities be tolerated.
(3) The "ecclesiastical reservation," or principle that when a Catholic spiritual prince became Protestant he should be deposed and a successor appointed {131} so that his territory might remain under the church.
In respect to this Ferdinand privately promised to secure toleration for Protestant subjects in the land of such a prince.

All claims of spiritual jurisdiction by Catholic prelates in Lutheran lands were to cease.

All estates of the church confiscated prior to 1552 were to remain in the hands of the spoliators, all seized since that date to be restored.
The Peace of Augsburg, like the Missouri Compromise, only postponed civil war and the radical solution of a pressing problem.