Prussia (German: Preußen; Old Prussian: Prūsa;) is a kingdom located in central Europe. It is bordered by Denmark to the north, the Russian Empire to the east, the Danubian Federation to the south, and France, Belgium, the Netherlands and Luxemburg to the west.
The name Prussia derives from the Old Prussians. In the 13th century, "Old Prussia" was conquered by German crusaders, the Teutonic Knights. In 1308, Teutonic Knights conquered the formerly Polish region of Pomerelia with Danzig. Their monastic state was mostly Germanized through immigration from central and western Prussia and in the south, it was Polonized by settlers from Masovia. After the Second Peace of Thorn of 1466, Prussia was split into the western Royal Prussia, a province of Poland, and the eastern part, since 1525 called 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 power shortly after becoming a kingdom and exercised the most influence on the German minorities, in an attempt to form the North German Federation, and then Germany. At the Congress of Vienna, which redrew the map of Europe following Napoleon's defeat, Prussia acquired a large section of North-Western Germany, including the coal-rich Ruhr.
As this is a alternate universe country, I will point you to the Prussia, just look at everything before 1848.
In the mid-16th century, the margraves of Brandenburg had become highly dependent on the estates (counts, lords, knights and towns, no prelates due to the Protestant Reformation in 1538). The margraviate's liabilities and tax income as well as the margrave's finances were controlled by the Kreditwerk, an institution not controlled by the elector, and the Großer Ausschuß ("Great Committee") of the estates. This was due to concessions made by Joachim II in 1541 in turn for financial aid by the estates, however, the Kreditwerk went bankrupt between 1618 and 1625. The margraves further had to yield the veto of the estates in all issues concerning the "better or worse of the country", in all legal commitments, and in all issues concerning pawn or sale of the elector's real property.
As of recent, Prussia has gained Alsace-Lorraine, which it has renamed to Elsass-Lothringen.
The Kingdom of Prussia was an absolute monarchy until the Revolutions of 1848 in the German states, after which Prussia became a constitutional monarchy and Adolf Heinrich von Arnim-Boitzenburg was appointed as Prussia's first prime minister. Following Prussia's first constitution, a two-house parliament was formed. The lower house, or Landtag was elected by all taxpayers, who were divided into three classes according to the amount of taxes paid. This allowed just over 25% of the voters to choose 85% of the legislature, all but assuring dominance by the more well-to-do elements of the population. The upper house, which was later renamed the Prussian House of Lords, was appointed by the king. He retained full executive authority and ministers were responsible only to him. As a result, the grip of the landowning classes, the Junkers, remained unbroken, especially in the eastern provinces. Prussian Secret Police, formed in response to the Revolutions of 1848 in the German states, aided the conservative government.