The Treaty of Westphalia was actually a pair of treaties negotiated in the Westphalian towns of Münster and Osnabrück and concluded on October 24, 1648, ending the Thirty Years’ War (1618–1648). The Thirty Years’ War, a period of violence and destruction unmatched in Europe until the twentieth century, had brought about a perspectival change in the way states dealt with one another. The medieval notion of universality, whereby rulers acted in the best interests of the church, had given way to the brutal emergence of raison d’état, or the view that state interests trump all other concerns. The treaty was the European community’s first attempt to reign in national aggression through fostering a balance of power and collective peace.