外交革命
After the War of the Austrian Succession, traditional European alliances fell apart and were replaced by an Anglo-Prussian pact and a Franco-Austrian alliance. Known as the Diplomatic Revolution, these events caused the Seven Years' War. Frederick II, King of Prussia and bitter rival of the Holy Roman Empress Maria Theresa of Austria, invaded Silesia in 1756 but suffered his first defeat at Kolin on June 18. In the aftermath of the battle, however, Frederick neglected to protect the approach to his capital, Berlin.