Question: The Melanchthon Circle was a 16th-century Lutheran intellectual network centred on the University of Wittenberg in Germany, and its leading theologian Philip Melanchthon, patronage came from which 37th Grand Master of the Teutonic Knights, who after converting to Lutheranism, became the first ruler of the Duchy of Prussia, the secularized state that emerged from the former Monastic State of the Teutonic Knights?

The state of Prussia had its origins in the separate lands of the Margraviate of Brandenburg and of the Duchy of Prussia.  The Margraviate of Brandenburg developed from the medieval Northern March of the Holy Roman Empire, passing to the House of Hohenzollern in 1415.  The Duchy of Prussia originated in 1525 when Albert of Brandenburg-Ansbach, a member of a cadet branch of the Hohenzollerns, secularized the eastern lands of the Teutonic Knights as a Polish fief.  Prince-elector John Sigismund, Elector of Brandenburg, inherited the Duchy of Prussia in 1618, thus uniting Brandenburg and Prussia under one ruler in a personal union; the Elector's state became known as Brandenburg-Prussia.  The Kingdom of Prussia formed when Elector Frederick III assumed the title of Frederick I, King in Prussia, on 18 January 1701. <SEP>  Albert was the first European ruler to establish Lutheranism, and thus Protestantism, as the official state religion of his lands.  He proved instrumental in the political spread of Protestantism in its early stage, ruling the Prussian lands for nearly six decades (1510–1568). Albert of Prussia (German: Albrecht von Preussen, 17 May 149020 March 1568) was the 37th Grand Master of the Teutonic Knights, who after converting to Lutheranism, became the first ruler of the Duchy of Prussia, the secularized state that emerged from the former Monastic State of the Teutonic Knights. <SEP> The Melanchthon Circle was a 16th-century Lutheran intellectual network centred on the University of Wittenberg in Germany, and its leading theologian Philip Melanchthon.  Patronage came from Albert, Duke of Prussia.  It was identified as significant for its interests in natural philosophy by Lynn Thorndike, in a chapter "The Circle of Melanchthon" in his multi-volume "History of Magic and Experimental Science".  Among this circle were found many of the most important early proponents of the heliocentric model of Copernicus.  They included Caspar Peucer who became Melanchthon's son-in-law, Erasmus Reinhold, and Georg Joachim Rheticus. <SEP> The monarchs of Prussia were members of the House of Hohenzollern who were the hereditary rulers of the former German state of Prussia from its founding in 1525 as the Duchy of Prussia.  The Duchy had evolved out of the Teutonic Order, a Roman Catholic crusader state and theocracy located along the eastern coast of the Baltic Sea.  The Teutonic Knights were under the leadership of a Grand Master, the last of whom, Albert, converted to Protestantism and secularized the lands, which then became the Duchy of Prussia.  The Duchy was initially a vassal of the Kingdom of Poland, as a result of the terms of the Prussian Homage whereby Albert was granted the Duchy as part of the terms of peace following the Prussian War.  When the main line of Prussian Hohenzollerns died out in 1618, the Duchy passed to a different branch of the family, who also reigned as Electors of Brandenburg in the Holy Roman Empire.  While still nominally two different territories, Prussia under the suzerainty of Poland and Brandenburg under the suzerainty of the Holy Roman Empire, the two states are known together historiographically as Brandenburg-Prussia.  Following the Second Northern War, a series of treaties freed the Duchy of Prussia from any vassalage to any other state, making it a fully sovereign Duchy in its own right.  This complex situation (where the Hohenzollern ruler of the independent Duchy of Prussia was also a subject of the Holy Roman Emperor as Elector of Brandenburg) laid the eventual groundwork for the establishment of the Kingdom of Prussia in 1701.  For diplomatic reasons, the rulers of the state were known as the King in Prussia from 1701 to 1772; largely because they still owed fealty to the Emperor as Electors of Brandenburg, the "King in Prussia" title (as opposed to "King of Prussia") avoided offending the Emperor.  As the Prussian state grew through several wars and diplomatic moves throughout the 18th century, it became apparent that Prussia had become a Great Power that did not need to submit meekly to the Holy Roman Empire.  By 1772, the pretense was dropped, and the style "King of Prussia" was adopted.  Thus it remained until 1871, when in the aftermath of the Franco-Prussian War, the King of Prussia Wilhelm I was crowned German Emperor.  From that point forward, though the Kingdom of Prussia retained its status as a constituent state of the German Empire, all remaining Kings of Prussia also served as German Emperor, and that title took precedence.