Claim: Prussia became part of a unitary country.

Prussia was a historical state originating out of the Duchy of Prussia and the Margraviate of Brandenburg , and centred on the region of Prussia . For centuries , the House of nocat = y ruled Prussia , successfully expanding its size by way of an unusually well-organised and effective army . Prussia , with its capital in Königsberg and from 1701 in Berlin , shaped the history of Germany . In 1871 , German states united to create the German Empire under Prussian leadership . In November 1918 , the monarchies were abolished and the nobility lost its political power during the German Revolution of 1918 -- 19 . The Kingdom of Prussia was thus abolished in favour of a republic -- the Free State of Prussia , a state of Germany from 1918 until 1933 . From 1933 , Prussia lost its independence as a result of the Prussian coup , when the Nazi regime was successfully establishing its Gleichschaltung laws in pursuit of a unitary state . With the end of the Nazi regime , the division of Germany into allied-occupation zones and the separation of its territories east of the -LSB- Oder -- Neisse , nocat = y -RSB- line , which were incorporated into Poland and the Soviet Union , the State of Prussia ceased to exist de facto in 1945 . Prussia existed de jure until its formal liquidation by the Allied Control Council Enactment No. 46 of 25 February 1947 .   The name Prussia derives from the Old Prussians . In the 13th century , the Teutonic Knights -- an organized Catholic medieval military order of German crusaders -- conquered the lands inhabited by them . In 1308 , the Teutonic Knights conquered the region of Pomerelia with Gdańsk -LRB- Danzig -RRB- . Their monastic state was mostly Germanised through immigration from central and western Germany and in the south , it was Polonised by settlers from Masovia . The Second Peace of Thorn -LRB- 1466 -RRB- split Prussia into the western Royal Prussia , a province of Poland , and the eastern part , from 1525 called the Duchy of Prussia , a fief of the Crown of Poland up to 1657 . The union of Brandenburg and the Duchy of Prussia in 1618 led to the proclamation of the Kingdom of Prussia in 1701 .   Prussia entered the ranks of the great powers shortly after becoming a kingdom , and exercised most influence in the 18th and 19th centuries . During the 18th century it had a major say in many international affairs under the reign of Frederick the Great . During the 19th century , Chancellor Otto von Bismarck united the German principalities into a `` Lesser Germany '' which excluded the Austrian Empire .   At the Congress of Vienna -LRB- 1814 -- 15 -RRB- , which redrew the map of Europe following Napoleon 's defeat , Prussia acquired a large section of north western Germany , including the coal-rich Ruhr . The country then grew rapidly in influence economically and politically , and became the core of the North German Confederation in 1867 , and then of the German Empire in 1871 . The Kingdom of Prussia was now so large and so dominant in the new Germany that -LSB- Junker -LRB- Prussia -RRB- , Junker -RSB- s and other Prussian élites identified more and more as Germans and less as Prussians .   The Kingdom ended in 1918 . In the Weimar Republic , the state of Prussia lost nearly all of its legal and political importance following the 1932 coup led by Franz von Papen . East Prussia lost all of its German population after 1945 , as Poland and the Soviet Union absorbed its territory and expelled most of its inhabitants .   The term Prussian has often been used , especially outside of Germany , to emphasise the professionalism , aggressiveness , militarism and conservatism of the Junker class of landed aristocrats in the East who dominated first Prussia and then the German Empire .