European Union law fair dealing through their business. In 1517, the Protestant Reformation triggered a hundred years of crisis and instability. Martin Luther nailed a list of demands to the church door of Wittenberg, King Henry VIII declared a unilateral split from Rome with the Act of Supremacy 1534, and conflicts flared across the Holy Roman Empire until the Peace of Augsburg 1555 guaranteed each principality the right to its chosen religion ("cuius regio, eius religio"). This unstable settlement unravelled in the Thirty Years' War (1618–1648), killing around a quarter of the population in central Europe. The Treaty of Westphalia 1648, which brought
Peace of Westphalia Peace of Westphalia The Peace of Westphalia () was a series of peace treaties signed between May and October 1648 in the Westphalian cities of Osnabrück and Münster, largely ending the European wars of religion. The treaties of Westphalia brought to a close a calamitous period of European history which caused the deaths of approximately eight million people. Scholars have identified Westphalia as the beginning of the modern international system, based on the concept of Westphalian sovereignty. The negotiation process was lengthy and complex. Talks took place in two different cities, as each side wanted to meet on territory under