The negotiation process was lengthy and complex. Talks took place in two cities, because each side wanted to meet on territory under its own control. A total of 109 delegations arrived to represent the belligerent states, but not all delegations were present at the same time. Two treaties were signed to end the war in the Empire: the Treaty of Münster and the Treaty of Osnabrück.  These treaties ended the Thirty Years' War in the Holy Roman Empire, with the Habsburgs (rulers of Austria and Spain) and their Catholic allies on one side, battling the Protestant powers (Sweden and certain Holy Roman principalities) allied with France, which was Catholic but strongly anti-Habsburg under King Louis XIV. The separate Peace of Münster ended the Eighty Years' War between Spain and the United Provinces.
Joachim Whaley, a leading English-language historian of the Holy Roman Empire, mentions that later commentators such as Leibniz, Rousseau, Kant, and Schiller eulogized the Peace of Westphalia as the first step towards a universal peace, but he points out that "their projections for the future should not be mistaken for descriptions of reality".
Scholars of international relations have identified the Peace of Westphalia as the origin of principles crucial to modern international relations, collectively known as Westphalian sovereignty, though other historians argue that this is largely a myth invented after the fact.
Europe had been battered by the Thirty Years' War and the Eighty Years' War, exacting a heavy toll in money and lives. The Eighty Years' War was a prolonged struggle for the independence of the Netherlands, supported by England, against Spain and Portugal. The Thirty Years' War was a partly religious, mostly dynastic power struggle. The war included a large number of players, siding either with the House of Habsburg or the House of Bourbon, though the factionalization was more complex than just dynastic allegiances. With between 4.5 million and 8 million dead in the Thirty Years' War alone, and decades of constant warfare, the need for peace became increasingly clear.
Peace negotiations between France and the HabsburgEmperor began in Cologne in 1636. These negotiations were initially blocked by Cardinal Richelieu of France, who insisted on the inclusion of all his allies, whether fully sovereign countries or states within the Holy Roman Empire.[page needed] In Hamburg, Sweden, France and the Holy Roman Empire negotiated a preliminary peace in December 1641. They declared that the preparations of Cologne and the Treaty of Hamburg were preliminaries of an overall peace agreement.
Dutch envoy Adriaan Pauw enters Münster around 1646 for the peace negotiations
The main peace negotiations took place in Westphalia, in the neighbouring cities of Münster and Osnabrück. Both cities were maintained as neutral and demilitarized zones for the negotiations.
In Münster, negotiations took place between the Holy Roman Empire and France, as well as between the Dutch Republic and Spain who on 30 January 1648 signed a peace treaty, that was not part of the Peace of Westphalia. Münster had been, since its re-Catholicisation in 1535, a strictly mono-denominational community. It housed the Chapter of the Prince-Bishopric of Münster. Only Roman Catholic worship was permitted, while Calvinism and Lutheranism were prohibited.
Sweden preferred to negotiate with the Holy Roman Empire in Osnabrück, controlled by the Protestant forces. Osnabrück was a bidenominational Lutheran and Catholic city, with two Lutheran churches and two Catholic churches. The city council was exclusively Lutheran, and the burghers mostly so, but the city also housed the Catholic Chapter of the Prince-Bishopric of Osnabrück and had many other Catholic inhabitants. Osnabrück had been subjugated by troops of the Catholic League from 1628 to 1633 and then taken by Lutheran Sweden.
The reverse of this medal: Christina of Sweden as Minerva holding an olive branch in her left arm and grasping the tree of knowledge with her right hand.
The peace negotiations had no exact beginning or end, because the 109 delegations never met in a plenary session. Instead, various delegations arrived between 1643 and 1646 and left between 1647 and 1649. The largest number of diplomats were present between January 1646 and July 1647.
Delegations had been sent by 16 European states, 66 Imperial States representing the interests of 140 Imperial States, and 27 interest groups representing 38 groups.
The power asserted by Ferdinand III was stripped from him and returned to the rulers of the Imperial States. The rulers of the Imperial States could henceforth choose their own official religions. Catholics and Protestants were redefined as equal before the law, and Calvinism was given legal recognition as an official religion. The independence of the Dutch Republic, which practiced religious toleration, also provided a safe haven for European Jews.
The Holy See was very displeased at the settlement, with Pope Innocent X calling it "null, void, invalid, iniquitous, unjust, damnable, reprobate, inane, empty of meaning and effect for all time" in the bullZelo Domus Dei.
The main tenets of the Peace of Westphalia were:
All parties would recognise the Peace of Augsburg of 1555, in which each prince had the right to determine the religion of his own state (the principle of cuius regio, eius religio). However, the ius reformandi was removed, subjects were no longer forced to follow the conversion of their ruler. Rulers were allowed to choose Catholicism, Lutheranism, or Calvinism.
1 January 1624 was defined as the normative date for determining the dominant religion of a state. All ecclesiastical property was to be restored to the condition of 1624. Christians living in principalities where their denomination was not the established church were guaranteed the right to practice their faith in private, as well as in public during allotted hours.
It is often argued that the Peace of Westphalia resulted in a general recognition of the exclusive sovereignty of each party over its lands, people, and agents abroad, as well as responsibility for the warlike acts of any of its citizens or agents.
The Old Swiss Confederacy was formally recognised as independent from the Holy Roman Empire, after decades of de facto independence.
The Dutch Republic, which had declared its independence from Spain in 1581, was formally recognised as a fully independent state from both Spain and the Holy Roman Empire.
To escape incorporation into Swedish Bremen-Verden, the city of Bremen had claimed Imperial immediacy. The emperor had granted this request and separated the city from the surrounding Bishopric of Bremen. Sweden launched the Swedish-Bremen wars in 1653/54 in a failed attempt to take the city.
The treaty ruled that the Dukes of Mecklenburg, owing their re-investiture to the Swedes, cede Wismar and the Mecklenburgian port tolls. While Sweden understood this to include the tolls of all Mecklenburgian ports, the Mecklenburgian dukes as well as the emperor understood this to refer to Wismar only.
The treaties did not entirely end conflicts arising out of the Thirty Years' War. Fighting continued between France and Spain until the Treaty of the Pyrenees in 1659. The Dutch-Portuguese War had begun during the Iberian Union between Spain and Portugal, as part of the Eighty Years' War, and went on until 1663. Nevertheless, the Peace of Westphalia did settle many outstanding European issues of the time.
Scholars of international relations have identified the Peace of Westphalia as the origin of principles crucial to modern international relations, including the inviolability of borders and non-interference in the domestic affairs of sovereign states. This system became known in the literature as Westphalian sovereignty.[page needed] Although scholars have challenged the association with the Peace of Westphalia, the debate is still structured around the concept of Westphalian sovereignty.
However, scholars have challenged the view that the modern European states system originated with the Westphalian treaties. The treaties do not contain anything in their text about religious freedom, sovereignty, or balance of power that can be construed as international law principles. Constitutional arrangements of the Holy Roman Empire are the only context in which sovereignty and religious equality are mentioned in the text, but they are not new ideas in this context. While the treaties do not contain the basis for the modern laws of nations themselves, they do symbolize the end of a long period of religious conflict in Europe.
^Konrad Repgen, 'Negotiating the Peace of Westphalia: A Survey with an Examination of the Major Problems', In: 1648: War and Peace in Europe: 3 vols. (Catalogue of the 26th exhibition of the Council of Europe, on the Peace of Westphalia), Klaus Bußmann and Heinz Schilling (eds.) on behalf of the Veranstaltungsgesellschaft 350 Jahre Westfälischer Friede, Münster and Osnabrück: no publ., 1998, 'Essay Volume 1: Politics, Religion, Law and Society', pp. 355–72, here pp. 355 seq.
^Konrad Repgen, "Negotiating the Peace of Westphalia: A Survey with an Examination of the Major Problems", In: 1648: War and Peace in Europe: 3 vols. (Catalogue of the 26th exhibition of the Council of Europe, on the Peace of Westphalia), Klaus Bußmann and Heinz Schilling (eds.) on behalf of the Veranstaltungsgesellschaft 350 Jahre Westfälischer Friede, Münster and Osnabrück: no publ., 1998, 'Essay Volume 1: Politics, Religion, Law and Society', pp. 355–372, here p. 356.
^The incipit of this bull, meaning "Zeal of the house of God", quotes from Psalm 69:9: "For the zeal of thine house hath eaten me up, and the reproaches of them that reproached thee are fallen upon me."
^Larry Jay Diamond; Marc F. Plattner; Philip J. Costopoulo (2005). World religions and democracy. p. 103.
^Mary Fulbrook A Concise History of Germany, 2nd ed. (Cambridge University Press, 2004), p. 60.
^Böhme, Klaus-R (2001). "Die sicherheitspolitische Lage Schwedens nach dem Westfälischen Frieden". In Hacker, Hans-Joachim (ed.). Der Westfälische Frieden von 1648: Wende in der Geschichte des Ostseeraums (in German). Kovač. p. 35. ISBN3-8300-0500-8.
^Randall Lesaffer (2014). "Peace treaties from Lodi to Westphalia". Peace Treaties and International Law in European History: From the Late Middle Ages to World War One. Cambridge. p. 9. ISBN978-0-511-21603-9.
Croxton, Derek, and Anuschka Tischer. The Peace of Westphalia: A Historical Dictionary (Greenwood Publishing Group, 2002).
Croxton, Derek (1999). "The Peace of Westphalia of 1648 and the Origins of Sovereignty". International History Review. 21 (3): 569–591. doi:10.1080/07075332.1999.9640869.
Mowat, R. B. History of European Diplomacy, 1451–1789 (1928) pp 104–14 online
Schmidt, Sebastian (2011). "To Order the Minds of Scholars: The Discourse of the Peace of Westphalia in International Relations Literature1". International Studies Quarterly. 55 (3): 601–623. doi:10.1111/j.1468-2478.2011.00667.x. Historiography.