Frederick William was Elector of Brandenburg and Duke of Prussia, thus ruler of Brandenburg-Prussia, from 1640 until his death in 1688. A member of the House of Hohenzollern, he is popularly known as "the Great Elector" because of his military and political achievements. Frederick William was a staunch pillar of the Calvinist faith, associated with the rising commercial class. He saw the importance of trade and promoted it vigorously. His shrewd domestic reforms gave Prussia a strong position in the post-Westphalian political order of Northern-Central Europe, setting Prussia up for elevation from duchy to kingdom, achieved under his son and successor.

The Margraviate of Brandenburg was a major principality of the Holy Roman Empire from 1157 to 1806 that played a pivotal role in the history of Germany and Central Europe.