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
Duchy of Limburg Eighty Years' War, ended by the 1648 Peace of Westphalia. An area known as Limburg of the States, consisting of parts of Overmaas (but no part of the Duchy of Limburg itself), was ceded to the Dutch Republic. In 1661, the Dutch and the Spanish agreed on a re-partition of the county of Dalhem. The duchy of Limburg itself remained undivided under Spanish Habsburg rule as part of the Southern Netherlands, passing to the Austrian Habsburgs under the Treaty of Utrecht in 1713. When the region was occupied by the French in 1794, the Austrian duchy of Limburg proper was