Prague Castle, site of negotiations
|Signed||30 May 1635|
|Location||Prague Castle, Bohemia|
|Mediators||George II of Hesse-Darmstadt|
|Negotiators|| Trauttmansdorff |
von Oppel 
| Emperor Ferdinand |
John George I
|Parties||Emperor Ferdinand |
John George I
The Peace of Prague, Pra?ský mír (Czech), Prager Frieden (German), signed on 30 May 1635, ended Saxony's participation in the Thirty Years War. The terms would later form the basis of the 1648 Peace of Westphalia.
Other German princes subsequently joined the treaty and although the Thirty Years War continued, it is generally agreed Prague ended it as a religious civil war within the Holy Roman Empire. Thereafter, the conflict was largely driven by foreign powers, including Spain, Sweden, and France.
The Thirty Years War began in 1618 when Frederick, Protestant ruler of the Palatinate, accepted the crown of Bohemia. Many Germans remained neutral, viewing it as an inheritance dispute, and with Bavarian support, Emperor Ferdinand quickly suppressed the Bohemian Revolt. Troops under Maximilian I, Elector of Bavaria, invaded the Palatinate in 1622 and sent Frederick into exile. However, depriving a hereditary prince of his lands changed both the nature and extent of the war.
Christian IV of Denmark invaded Northern Germany in support of his fellow Protestants, until defeated and forced to withdraw in 1629. Success led Ferdinand to pass the Edict of Restitution, requiring any property transferred since 1552 restored to its original owner, in nearly every case, the Catholic Church. By effectively undoing the 1555 Peace of Augsburg, it forced moderate Protestants like John George of Saxony and George William of Brandenburg into opposition. This increased after 1627 by having a large Imperial army based on their lands, whose rarely paid troops simply took what they wanted.
Conflicts in 17th century Europe often drew in foreign participants, because of the rivalry between the Bourbon kings of France, and their Habsburg rivals in Spain and the Holy Roman Empire. Habsburg territories in the Spanish Netherlands, Franche-Comté, and the Pyrenees blocked French expansion, and made it vulnerable to invasion. As a result, the Catholic Bourbons supported Habsburg opponents, irrespective of religion, including the Ottomans, Dutch, and Danes.
In 1630, Gustavus Adolphus of Sweden invaded Pomerania with French money, and support from Saxony and Brandenburg-Prussia. After his death at Lützen in 1632, Sweden formed the Heilbronn League; composed of smaller Protestant states and funded by France, the League won a series of victories, until defeated at Nördlingen in 1634.
This re-established a military balance, while also highlighting differences between the Heilbronn members. Sweden sought to preserve its grip on the lucrative Baltic trade, and retain their post-1630 acquisition of Swedish Pomerania. To strengthen their borders in the Rhineland and the Low Countries, France supported the Dutch, Swedish competitors in the Baltic, and Maximilian of Bavaria, a leader of the anti-Swedish Catholic League. Their German allies wanted to restore the territorial position of 1618, which implied reversing French and Swedish gains.
After 1632, Ferdinand accepted Catholicism could not be re-imposed by force and opened discussions on amending the Edict of Restitution in February 1633, eighteen months before Nördlingen. The execution of Imperial commander Wallenstein in February 1634 removed a major obstacle, since he had become an independent agent. With the Lutheran states of Denmark-Norway and Hesse-Darmstadt acting as mediators, the two parties agreed a preliminary draft in November 1634, known as the 'Pirnaer Noteln'. Although subject to many corrections and revisions, this was the basis of the 1635 agreement.
The treaty was a bilateral agreement between Ferdinand and John George, with other states joining later. Negotiations were held in Prague Castle, site of the Defenestration that began the war in 1618, and took eight days. Its terms included the following;
Many others subsequently joined the treaty, some of whom received minor concessions; Brandenburg-Prussia was confirmed as holder of Farther Pomerania, previously a possession of the last Duke Bogislaw XIV. Those who joined included Bavaria, Hesse-Darmstadt, the dukes of Saxe-Weimar, Saxe-Gotha and Mecklenburg-Schwerin, and Archbishops of Mainz and Cologne.
In 1623, Saxony occupied the Bohemian crown lands of Lower and Upper Lusatia, in return for their support during the Bohemian Revolt. Under the Traditionsrezess annex of 1636, Ferdinand ceded both territories in perpetuity, plus the towns of Jüterbog, Dahme and Burg Querfurt. John George also received the Archbishopric of Magdeburg and Halberstadt, after agreeing not to secularise them; these were transferred to Brandenburg-Prussia in 1648.
While Ferdinand continued the Counter-Reformation in his own lands, it is generally agreed the Peace of Prague ended it as an internal religious conflict, and established the principle of cuius regio, eius religio. By renouncing their right to create alliances and handing over control of armed forces, the Imperial estates in return acknowledged the supremacy of the Emperor.
However, these principles were not universally followed and hostilities continued, including a bitter civil war between Hesse-Darmstadt and Hesse-Kassel, as well as foreign intervention. On 19 May 1635, France declared war on Spain; while his brother William joined the Peace with the duchy of Saxe-Weimar, Bernard of Saxe-Weimar and his army were employed by France against Spanish possessions in Lorraine and the Rhineland. In 1642, Sweden won a resounding victory at Second Breitenfeld, over-running Saxony. This prompted many German states to fight on, hoping to improve their position and peace was not finally achieved until the Peace of Westphalia in 1648.