an early mercantilist entrepreneur. As a typical duke of his time, he expressed his wealth with various buildings and founded, among other things, the castles in Reinfeld and Ahrensbök, which have since been demolished. He modernized the Sønderborg Castle and in 1582 began building Glücksburg castle, where the Ryd Abbey used to be. The castle was built to serve as a comfortable country castle for himself and his family. After John's death in 1622, the duchy of Schleswig-Holstein-Sonderburg was divided amongst his heirs. John's son Philipp received the castle and the lands of Glücksburg and thus founded the first, the elder line of the House of Schleswig-Holstein-Sonderburg-Glücksburg. The castle remained the seat of the Dukes of Glücksburg for over 150 years, but the small titular duchy itself remained relatively insignificant. Apart from the fact that the members of the house were repeatedly married into other noble families, they played no role in the history of the country. During this time, the Glücksburg castle was more of a continuously inhabited noble family seat and less of a courtly residence. In the middle of the 17th century, the palace and its outbuildings housed a court of an average of 80 people. Descendants of John († 1622) who resided Glücksburg Castle after his death: Philipp (Schleswig-Holstein-Sonderburg-Glücksburg), † 1663 Christian (Schleswig-Holstein-Sonderburg-Glücksburg), † 1698 Philipp Ernst (Schleswig-Holstein-Sonderburg-Glücksburg), † 1729 Friedrich. (Schleswig-Holstein-Sonderburg-Glücksburg), † 1766 Friedrich Heinrich Wilhelm (Schleswig-Holstein-Sonderburg-Glücksburg), † 1779 With the death of the childless Friedrich Heinrich Wilhelm in 1779, the older branch of the family went extinct and the Glücksburg fief went back to the Danish royal family. Until 1824 the wife of the last Duke, Anna Carolina used the castle as a widow's residence. The ancestral seat of the younger line in 1825, The Danish King Frederick VI handed over the fief and thus the castle and title to his brother-in-law Friedrich Wilhelm from the Holstein-Beck family. Friedrich Wilhelm assisted the Danish king during the Congress of Vienna and was accordingly rewarded with the Ducal title. Raised in Denmark and Prussia, the new duke was a direct descendant of the palace's builder, John III. Together with his wife, Louise Caroline, a daughter of the ducal governor Charles von Hessen-Kassel, he founded the younger line of the House of Glücksburg. Friedrich Wilhelm no longer lived in the castle himself; however, his wife resided here until the first Schleswig War. Among their ten children was