Prussia becomes a kingdom in 1701
Frederick III (1657-1713) crowns himself on 18 January 1701 to become Prussian king that he thence rules over as Frederick I. He had previously gained the approval of Emperor Leopold II for being raised to royal status by supporting the emperor financially and militarily in the Turkish Wars. He is, however, only permitted to bear this title in the territory of the Duchy of Prussia not directly belonging to the Holy Roman Empire.
Because parts of Prussia continue to be subject to the feudal sovereignty of Poland up until the Partitions of Poland in the second half of the 18th century, the first Brandenburg kings are "in" and Frederick the Great is the first to be King "of" Prussia.
In 1701 King Frederick I in this way lays the foundation for the rise of Prussia to become a major European power in the 18th century. The name of Prussia is passed to all possessions and estates.