The Reichstag declares an “imperial war” against Prussia

Frederick II followed his coronation as King in Prussia with the conquest of the Austrian province of Silesia. Even after two lost wars, the Austrian Queen Maria Theresa refused to give up and forged an alliance with France and Russia; Prussia in turn allied with Great Britain. In 1756, the colonial powers Great Britain and France declared war on each other, and tensions increased in Central Europe.

26 August 1756 saw Prussia invade Saxony without declaring war. If that was not bad enough, Frederick then defeated an Austrian army in Bohemia. Appalled at this level of aggression, the Imperial Diet in Regensburg declared war on Prussia on 17 January 1757.

What later became known as the Seven Years’ War ended with a Prussian victory, marking its rise to become the fifth greatest power in Europe.