The Treaty of Westphalia refers to a series of peace agreements signed in 1648 that ended the Thirty Years' War in Europe. This conflict involved many countries and was primarily fought over religious and political disputes between Catholics and Protestants. The treaties marked a significant turning point in European history, establishing the principles of state sovereignty and non-interference in the internal affairs of other nations. The agreements resulted in territorial changes and recognized the independence of several states, including the Dutch Republic and Switzerland. The Treaty of Westphalia is often credited with laying the groundwork for the modern international system, where countries respect each other's borders and sovereignty.