What was the Peace of Westphalia?

The Peace of Westphalia was a treaty agreement between Spain and the Dutch in 1648. This agreement put an end to the Thirty Years' War. The peace of Westphalia is recognized to be the beginning of modern international relations based on the recognition of state sovereignty. Westphalia recognized sovereignty of Netherlands and German states which meant that Europe would not unite under an emperor. This also meant the decline for the Habsburg monarchy and papal authority who enjoyed support from Phillip II of Spain.