Brandenburg–Prussia

Brandenburg-Prussia (German: Brandenburg-Preußen; Low German: Brannenborg-Preußen) is the historiographic denomination for the early modern realm of the Brandenburgian Royal dynasty of the House of Hohenzollern between 1618 and 1701. Based in the Electorate of Brandenburg, the main branch of the Hohenzollern intermarried with the branch ruling the Duchy of Prussia, and secured succession upon the latter's extinction in the male line in 1618.

Another consequence of the intermarriage between the nobility was the acquisition / incorporation of the lands far to the west of Brandenburg-Prussia located in western Germany of the Holy Roman Empire (A.D. c. 800 / 962 to 1806), and situated in the lower Rhenish / Rhine River of the principalities of the Duchy of Cleves, County of Mark and County of Ravensberg after the signing and agreements in the Treaty of Xanten in 1614.

The Thirty Years' War (1618–1648) was especially devastating. The Elector changed sides three times, and as a result Protestant groups of Evangelical Lutheran / Reformed / Calvinist and opposing Roman Catholic armies swept the lands back and forth, killing, burning, seizing men and confiscating any food or useful supplies. It is estimated that upwards of half the population of Central Europe / Germany of the late Medieval / Middle Ages period were killed or dislocated. Berlin and the other major cities were in ruins, and recovery took decades. By the Peace of Westphalia, which ended the Thirty Years' War in 1648, Brandenburg also gained the Bishopric of Minden and Principality of Halberstadt, also the succession in the Farther Pomerania (incorporated in the Treaty of Stettin of 1653), and the Duchy of Magdeburg (incorporated later in 1680). With the Treaty of Bromberg (1657), these concluded during the Second Northern War (1655-1660), the electors were also freed of old Polish vassalage and loyalty by the Treaty of Cracow gaining more independence for the Duchy of Prussia and gained territories of Lauenburg–Bütow and Draheim. The Treaty of Saint-Germain-en-Laye (1679) expanded the province of Brandenburgian Pomerania to the lower Oder River.

The second half of the 17th century laid the basis for Prussia to become one of the great players in European politics. The emerging Brandenburg-Prussian military potential, based on the introduction of a standing army in 1653, was symbolized by the widely noted victories in the Battle of Warsaw in 1656 and Battle of Fehrbellin (1675) and by the Great Sleigh Drive (1678). Brandenburg-Prussia also established a Brandenburg Navy for on the nearby waters of the Baltic Sea, Gulf of Finland and passages west to the North Sea with access to the North Atlantic Ocean and additional German colonies were established along the Brandenburger Gold Coast and Arguin. Frederick William, known as "The Great Elector", opened up his realm of Brandenburg-Prussia to large-scale immigration ("Peuplierung") of mostly Protestant refugees from all across Europe ("Exulanten"), most notably Huguenot immigration from France following the Edict of Potsdam. Frederick William also started to centralize Brandenburg-Prussia's administration and reduce the influence of the outlying landed estates.

In 1701, Frederick III, Elector of Brandenburg, succeeded in elevating his status to the title of King in Prussia. This was made possible by the Duchy of Prussia's sovereign status outside the jurisdiction of the Holy Roman Empire of the German Nation, and approval by the Royal House of Habsburg in Vienna in Austria, and the Holy Roman Emperor and other European royals in the course of forming alliances for the War of the Spanish Succession and the Great Northern War. From 1701 onward, the Hohenzollern dynasty domains were referred to as the Kingdom of Prussia, or simply Prussia. Legally, the personal union between Brandenburg and Prussia continued until the dissolution of the Holy Roman Empire by Napoleon Bonaparte in 1806. However, by this time the emperor's overlordship over the empire had become in recent decades of a "figleaf" legal fiction. Hence, after 1701, Brandenburg was de facto treated as part of the Prussian kingdom. Frederick and his successors continued to centralize and expand the state, transforming the personal union of politically diverse principalities typical for the Brandenburg-Prussian era into a system of provinces subordinate to the Stadtschloss, Berlin (Royal or Berlin Palace) in the capital city of Berlin.