The major treaty that ended the Thirty Years' War in Europe was the Peace of Westphalia, signed in 1648. This series of treaties concluded a conflict primarily involving various European powers, particularly in the Holy Roman Empire, which was marked by religious and territorial disputes. The Peace of Westphalia is significant as it established important precedents in international law, recognizing the sovereignty of states and their right to self-determination. It also marked a turning point in European politics, as the treaty sought to resolve the religious conflicts between Catholics and Protestants and laid the groundwork for modern nation-states.