The Peace of Westphalia was a series of peace treaties signed between May and October 1648 in Osnabrück and Münster. These treaties ended the Thirty Years' War (1618–1648) in the Holy Roman Empire, and the Eighty Years' War (1568–1648) between Spain and the Dutch Republic, with Spain formally recognizing the independence of the Dutch Republic.
The Peace of Westphalia, when all the war parties came together, was the first time that a European community of sovereign states was established. And it was only possible because all of its members recognized each other as having equal legal standing, and guaranteed each other their independence. They had to recognize their international legal treaties as binding, if they wanted to be an international community of law.
The Thirty Years' War has been described as the last major European war of religion and the first all-European struggle for power. It was literally a series of wars, fought mainly on German soil, and was in large part a struggle to alter the European balance of power.
The Thirty Years' War was also an international war between France and Spain and a dynastic war between the Bourbons and the Hapsburgs. Foreign powers opposed to the Hapsburgs could not look with equanimity on developments in Germany. The French, English and Dutch formed a league to oppose the Hapsburgs.
By 1643 preparations for the peace congress were sufficiently advanced for diplomats to begin their work in Münster and Osnabrück, but it was not until 1645 that the major delegations arrived and negotiations fully got under way. This was the largest international congress ever attempted in Europe, and there were no self-evident precedents to which delegates could turn for guidance.
Peace settlements began in 1643 with the ambassadors of the combatants meeting in peace congresses in Westphalia. The relative position of parties continued to change when there was no immediate truce, with all parties wanting to negotiate from a position of strength. Therefore it took 5 years to conclude peace, beginning in January 1648 between Spain and the United Provinces.
The main obstacles to a general peace in Germany after 1635 were the ambitions of France and Sweden and changing military fortunes. Sweden wanted territorial and financial compensation while France, under the cardinals (Richelieu to 1642, Mazarin thereafter), envisaged something altogether more ambitious that involved a considerable reduction in both Spanish and Austrian Habsburg power. In addition, matters were complicated by the individual ambitions of various German princes and separate negotiations between the Spanish and the Dutch.
The Peace of Westphalia consecrated the principle of toleration by establishing the equality between Protestant and Catholic states and by providing some safeguards for religious minorities. To be sure, the principle of liberty of conscience was applied only incompletely and without recriprocity.
The principles of tolerance of the Peace of Westphalia were not born out of a deeper understanding of Christian love, but rather out of a growing indifference to religion accompanied by the feeling, even among those of deep religious commitments, that such commitments should remain private, and not be carried into civil and political life. The war had amply shown the atrocities that resulted from attempting to settle religious matters by force of arms.
As the traditional bearers of the office of the Holy Roman Emperor of the German Nation, however, the Habsburgs effectively lost their ability to intervene in the affairs of the German empire because the Peace of Westphalia recognized a multitude of German states as sovereign entities. In this respect, the Habsburgs and the idea of the German empire as some kind of cohesive whole were losers, whereas the numerous German states and their rules were winners because they factually and formally were emancipated from the venerable constraints of the emperor and the empire. This event not only marks the beginning of the Habsburgs' long but gradual departure from a position of predominance in German politics, but the idea of "territorial sovereigns" also cemented the German tradition of particularism and disunity for the next two centuries.
The Treaty of Westphalia (1648) reflected and proclaimed a conception of international political order that gradually extended itself from its European roots to encompass most of the world. It was a conception built around the central importance of a particular type of political actor — the territorial, sovereign state.