The Treaty of Westphalia, signed in 1648, aimed to bring an end to the Thirty Years' War and the Eighty Years' War between Spain and the Dutch Republic. This landmark agreement established the principles of national sovereignty and the right of states to govern their own affairs without external interference. The treaty recognized the coexistence of Protestant and Catholic states, ultimately leading to a more religiously tolerant Europe. It marked a significant shift in international relations, laying the groundwork for modern diplomacy and contributing to the development of the state system that characterizes contemporary politics.