Deeply influenced by the horrors of the Thirty Years’ War (1618-1648), the Elector, ruling from 1640, tried to protect his widely scattered territory stretching from the Duchy of Prussia via the Margraviate of Brandenburg to the Lower Rhine with a standing army. In 1655 the Nordic war between Sweden and Poland-Lithuania broke out, in which Prussia was also involved. Representing a relevant military power and after changing sides several times, the Elector succeeded on the basis of the treaties of Wehlau 1657 and Oliva 1660 in negotiating the feudal independence of the Duchy of Prussia from Poland. However, in particular in Masuria the population was reduced by half during the war through violence and pillaging (the so-called Tartar invasion), epidemics and hunger.
With an iron fist, the Elector prevailed against the rebellious Prussian estates (Königsberg Uprising), thus laying the foundations for a centralist Brandenburg-Prussian administration and establishing himself as the absolute sovereign.
Illustration:
Wilhelm Simmler: Hunt across the Curonian Lagoon, sketch of a painting for the Berlin Hall of Fame, 1883/86.
In the Brandenburg-Swedish War (1674-1679) the "Great Elector" gained his nickname through the victory at Fehrbellin in 1675 and an unusual winter campaign in January 1679, during which the Prussian troops drove the Swedes out of the Duchy of Prussia with more than 1,000 sleighs. The Elector’s original sleigh could be admired for a long time in Königsberg Castle.