Prussia was a monarchy in Central and Northern Europe and one of the mightiest great powers of the 18th and 19th century.
Prussia was formed in 1525 by Albert of Prussia from the German dynasty of Hohenzollern, who was from 1510 to 1525 the Grand Master of the Knights Teutonic as well as the leader of the German crusader state along the Baltic Sea and, because of that, most likely a Templar. In 1523 he decided, on the advice of church reformer Martin Luther, to resign from his office as Grand Master and turned his country into a secular monarchy: The Duchy of Prussia.
Seven Years' War
In the 18th Century, Prussia already had the status of a great power, after becoming a kingdom in 1701 and winning the War of the Austrian Succession in 1748. When the Seven Years' War started in 1754, Prussia under Frederick the Great backed the United Kingdom, which led to the victory of their alliance in 1763.