East Prussia

East Prussia (German: Ostpreußen, ; Latin: Borussia orientalis) was the main part of the region of Prussia along the southeastern Baltic Coast from the 13th century to the end of World War II in May 1945. From 1772–1829 and 1878–1945, the Province of East Prussia was part of the German state of Prussia. The capital city was Königsberg.

East Prussia enclosed the bulk of the ancestral lands of the Baltic Old Prussians. During the 13th century, the native Prussians were conquered by the crusading Teutonic Knights. The indigenous Balts who survived the conquest were gradually converted to Christianity. Because of Germanization and colonisation over the following centuries, Germans became the dominant ethnic group, while Poles and Lithuanians formed minorities. From the 13th century, East Prussia was part of the monastic state of the Teutonic Knights, which became the Duchy of Prussia in 1525. The Old Prussian language had become extinct by the 17th or early 18th century.

Following the death of Hohenzollern Albert of Brandenburg Prussia, Duke of Prussia (1525–1568), Joachim II, the prince-elector Kurfürst of Brandenburg, became co-inheritor of Ducal Prussia. In 1577, House of Hohenzollern co-regents took over administration from Albert's only son, Albert Friedrich. In 1618 the Duchy of Prussia again passed by inheritance and in personal union with the Hohenzollerns of Brandenburg and the territory was called Brandenburg-Prussia. The territories of the House of Hohenzollern were scattered in Franconia, Brandenburg, eastern Prussia and elsewhere.

Because the duchy was outside of the core Holy Roman Empire (Prussia was under HRE administration by the Teutonic Order grandmasters), the prince-electors of Brandenburg were able to proclaim themselves kings in Prussia beginning in 1701. After the annexation of most of western Royal Prussia in the 1772 First Partition of the Polish-Lithuanian Commonwealth, East Prussia was connected by land with the rest of the Prussian state and was reorganized as the Province of East Prussia the following year. Between 1829 and 1878, the Province of East Prussia was joined with West Prussia to form the Province of Prussia.

The Kingdom of Prussia became the leading state of the German Empire after its creation in 1871. However, the Treaty of Versailles following World War I restored West Prussia to Poland and made East Prussia an exclave of Weimar Germany, while the Memel Territory was detached and was annexed by Lithuania in 1923. Following Nazi Germany's defeat in World War II in 1945, war-torn East Prussia was divided at Joseph Stalin's insistence between the Soviet Union (the Kaliningrad Oblast in the Russian SFSR and the constituent counties of the Klaipėda Region in the Lithuanian SSR) and the People's Republic of Poland (the Warmian-Masurian Voivodeship). The capital city Königsberg was renamed Kaliningrad in 1946. The German population of the province was largely evacuated during the war or expelled shortly thereafter in the expulsion of Germans after World War II. An estimated 300,000 (around one fifth of the population) died either in war time bombings raids or the battles to defend the province.