The Pope's reaction to the Treaties of Münster and Osnabrück is understandable. The Thirty Years War had raged across Bohemia, Germany, Italy, France, and the United Provinces, pitting nascent states against empires, rebellious princes against the Holy Roman Emperor, free cities against imperial cities, and Catholics against Protestants. The Pope condemned the outcome of four years of negotiations that led to the Peace of Westphalia because it confirmed the religious schism begun by Luther and significantly reduced the political authority of the Holy Roman Emperor and the other great symbol of Christian unity, the papacy. The Peace of Westphalia organized Europe on the principle of particularism. It represented a new diplomatic arrangement – an order created by states, for states – and replaced most of the legal vestiges of hierarchy, at the pinnacle of which were the Pope and the Holy Roman Emperor.

The Congresses of Münster and Osnabrück, which produced the Treaties of Westphalia, were the first of their kind. Europe had not previously witnessed a multilateral diplomatic gathering that was designed both to terminate a pan-European war and to build some sort of order out of the chaos into which Europe had increasingly fallen since the late fifteenth century. The congresses brought together the main heterogeneous political units of Europe at that time.