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
War of the Fifth Coalition not been able to save Prussia. The Russian and French armies met in February 1807 at the savage and indecisive Battle of Eylau, which left behind between 30,000–50,000 casualties. Napoleon regrouped his forces after the battle and continued to pursue the Russians in upcoming months. The action in Poland finally culminated on 14 June 1807, when the French mauled their Russian opponents at the Battle of Friedland. The resulting Treaty of Tilsit in July ended two years of bloodshed and left France as the dominant power on the European continent. It also severely weakened Prussia and formed a Franco-Russian axis