What was the significance of the Treaty of Westphalia?

The Treaty of Westphalia, which concluded in 1648, is significant primarily because it codified the principles of state sovereignty and non-interference in the affairs of other states. This treaty ended the Thirty Years' War in Europe and set a precedent for the modern international system, leading to the recognition of territorial integrity and the idea that nations should have the authority to govern themselves without external intervention.

By establishing these principles, the Treaty of Westphalia marked a turning point in international relations, as it laid the groundwork for the development of the nation-state as a primary actor in global politics. This shift helped to define a new order of diplomatic relations based on recognized borders and the rights of states, which continues to be a foundational aspect of international law and relations today.

The other choices mention events or institutions that occurred much later or were developed under different contexts. For example, the United Nations was established in the aftermath of World War II to promote peace and cooperation among nations, which is distinct from the context of the Westphalian treaties. The end of World War I occurred in 1918, long after the treaties, and collective security measures emerged in the 20th century as a response to the failures of the interwar period and