Peace of Augsburg #

Signed 25 September 1555 in Augsburg, Holy Roman Empire. Officially ended the religious war between Emperor Charles V and the Schmalkaldic League, and made the legal division of Christianity permanent within the Empire. ^[raw/articles/wikipedia-thirty-years-war-2026-06-14.md]

Core Principle: cuius regio, eius religio #

Latin for "whose realm, his religion." Each prince chose either Catholicism or Lutheranism as the official confession of his territory. Subjects had to conform or emigrate, with the right to sell their estates after paying taxes. Serfs were explicitly excluded from this emigration right. ^[raw/articles/wikipedia-thirty-years-war-2026-06-14.md]

Three Interlocking Rules #

1. Cuius regio, eius religio — ruler's religion became the state's religion.
2. Reservatum ecclesiasticum — if an ecclesiastical ruler (a bishop/abbot) converted to Lutheranism, he was expected to resign; his territory did not have to convert with him.
3. Declaratio Ferdinandei — exempted certain knights and cities from forced uniformity if they had been practicing Lutheranism since the mid-1520s. Added unilaterally by Ferdinand and kept secret for almost two decades.

What It Didn't Cover #

The treaty explicitly protected only Catholicism and Lutheranism. Calvinism, Zwinglianism, and Anabaptism had no legal standing. This made the settlement fragile.

Why It Collapsed #

It was a stopgap. By the early 17th century, Calvinism had spread into the Empire, and the excluded Protestant territories had no legal protection. The settlement "collapsed in the early 17th century, contributing directly to the outbreak of the Thirty Years' War." ^[raw/articles/wikipedia-thirty-years-war-2026-06-14.md]

Linked #

• [[thirty-years-war|Thirty Years' War]]
• [[reformation|Reformation]]
• [[holy-roman-empire|Holy Roman Empire]]
• [[edict-of-restitution|Edict of Restitution]] — reactivated the Augsburg settlement in an attempt to reverse Protestantism.
• [[peace-of-westphalia|Peace of Westphalia]] — expanded Augsburg by adding Calvinism and making some cities religiously mixed.