The Peace of Augsburg

By 1555 the Holy Roman Empire had spent a generation failing to suppress the Lutheran territories by law and by war, and the settlement reached at the Diet of Augsburg accepted the failure. Each imperial estate would determine whether its territory followed the old religion or the Augsburg Confession, and subjects who could not accept their ruler's choice were granted the right to emigrate with their property.

The tag by which the principle is known, cuius regio, eius religio, whose realm, his religion, was coined by a jurist some decades later and is not in the text, but it describes the arrangement accurately enough. Religion became an attribute of territory, decided by whoever held it.

Two devices were added to stop the settlement unravelling in one direction. The ecclesiastical reservation provided that a prince-bishop who converted must resign his see rather than take the territory with him, which preserved the Catholic bloc in the imperial constitution. A separate declaration protected some Lutheran subjects in ecclesiastical territories, and its status was disputed almost immediately.

The peace was a genuine achievement and it held, imperfectly, for over sixty years. It was also the first admission in imperial law that Latin Christendom would not be reunited, made by people who had grown up assuming that it must be.

The settlement's fatal limitation was its guest list. It recognised two religions: the Catholic Church and the adherents of the Augsburg Confession. Everyone else had no standing whatever.

That excluded the Reformed churches, which were spreading rapidly in the empire in the decades after 1555, and it excluded the Anabaptists entirely, who were prosecuted under laws that both recognised confessions were content to leave in force. A Reformed prince who converted his territory had, in strict law, no protection at all, and Catholic jurists said so.

The problem compounded as the confessional map moved. Rulers converted, territories changed hands, and disputes over ecclesiastical lands secularised after the reservation was supposed to prevent it accumulated without a mechanism to settle them. The imperial courts deadlocked along confessional lines. By the second decade of the seventeenth century the estates had formed armed confessional leagues, and the machinery of the peace had stopped working before the Thirty Years War began.

Westphalia in 1648 addressed the omission directly, extending the settlement to the Reformed and fixing a reference year against which contested church property would be judged. The lesson its negotiators drew from ninety years of experience is visible in the drafting: a religious settlement that leaves out a party growing fast enough to matter is a postponement rather than a peace.