A German state, the nucleus of the kingdom of Prussia. German conquest of its Slavic population began in the early 12th century. The margravate (established c.1157) took its name from the town of Brandenburg, west of Berlin. In 1356 the margrave’s status as an imperial Elector was confirmed by the Golden Bull of Charles V.

Strong central government began with the advent of the Hohenzollern dynasty in 1415. Brandenburg accepted the Lutheran Reformation after 1540, and in the early 17th century it acquired further territories in western Germany and also Prussia (1618). After an initial period of neutrality during the Thirty Years War, Frederick William (the Great Elector) (1620–88) entered the fighting and secured excellent terms at the Treaty of Westphalia (1648). He subsequently achieved full sovereignty in Prussia (1660) and turned Brandenburg-Prussia into a centralized European power with a highly effective army and bureaucracy. He used the opportunity offered him by Louis XIV’s persecution of the Huguenots to develop his country’s industry and trade. In 1701 Elector Frederick III (1657–1713) was granted the title of King in Prussia, and from that time Brandenburg was a province of the Prussian kingdom.