The Peace of Westphalia is the collective name for two peace treaties signed in October 1648 in the Westphalian cities of Osnabrück and Münster. They ended the Thirty Years' War (1618–1648) and brought peace to the Holy Roman Empire, closing a calamitous period of European history that killed approximately eight million people. Holy Roman Emperor Ferdinand III, the kingdoms of France and Sweden, and their respective allies among the princes of the Holy Roman Empire, participated in the treaties.

International relations (IR) are the interactions among sovereign states. The scientific study of those interactions is also referred to as international studies, international politics, or international affairs. In a broader sense, the study of IR, in addition to multilateral relations, concerns all activities among states—such as war, diplomacy, trade, and foreign policy—as well as relations with and among other international actors, such as intergovernmental organizations (IGOs), international nongovernmental organizations (INGOs), international legal bodies, and multinational corporations (MNCs). There are several schools of thought within IR, of which the most prominent are realism, liberalism and constructivism.