King in Prussia
The Kingdom of Prussia emerged as the leading state of the Empire. Frederick III (1688–1701) became King Frederick I of Prussia in 1701. Since there was only one King of the Germans within the Empire, Frederick gained the assent of Emperor Leopold I (in return for alliance against France in the War of the Spanish Succession) to his adoption (January 1701) of the title of "King in Prussia" based on his non-imperial territories. The title came into general acceptance with the Treaty of Utrecht (1713).