Friedrich Wilhelm, Duke Of Schleswig-Holstein-Sonderburg-Glücksburg

Friedrich Wilhelm, Duke of Schleswig-Holstein-Sonderburg-Glücksburg (German: Friedrich Wilhelm Paul Leopold; Danish: Frederik Vilhelm Paul Leopold), was born on 4 January 1785 at Lindenau manor house near Braunsberg in East Prussia, a region which is today Lipowina in Poland. He was the youngest child and only son of Friedrich Karl Ludwig, Duke of Schleswig-Holstein-Sonderburg-Beck, and Countess Friederike of Schlieben. His family was part of the ducal house of Schleswig-Holstein-Sonderburg-Beck, a junior branch of the House of Oldenburg, descending from King Christian III of Denmark through his younger son, Duke John the Younger. The family originated from the manor of Haus Beck in Westphalia, after which the lineage was named.

Friedrich Wilhelm received his early education at home, and from 1798 to 1802 attended a knight academy in Brandenburg an der Havel. He later studied at the University of Leipzig starting in 1803. Due to familial connections, he was sent in 1804 to Denmark-Norway, where his godfather, Crown Prince Frederick of Denmark, appointed him a rittmeister in the Royal Horse Guards. In 1805, he was transferred to the Duchy of Holstein to serve as second rittmeister in the Life Regiment Dragoons, a post that involved border guard duties. During this period, he participated in reconnaissance missions, demonstrating military aptitude. Following the British bombardment of Copenhagen in 1807 and Denmark's subsequent alliance with France, Friedrich Wilhelm returned to Copenhagen to continue his military service.

In 1809, Friedrich Wilhelm was promoted to major at the general staff of the duchies of Schleswig and Holstein, stationed at Gottorp Castle. It was there he met Princess Louise Caroline of Hesse-Kassel, the youngest daughter of Prince Charles of Hesse-Kassel and granddaughter of Frederik V of Denmark. They became engaged in November 1809 and married on 26 January 1810 in a private ceremony at Gottorp Castle. Through this marriage, Friedrich Wilhelm became brother-in-law to King Frederick VI of Denmark, as his wife’s elder sister, Marie of Hesse-Kassel, was married to the king. The couple had ten children.

Upon the death of his father on 25 March 1816, Friedrich Wilhelm inherited the title of Duke of Schleswig-Holstein-Sonderburg-Beck. After the elder Glücksburg line became extinct in 1824, the Danish King Frederick VI transferred Glücksburg Castle to Friedrich Wilhelm and changed his ducal title to Duke of Schleswig-Holstein-Sonderburg-Glücksburg in 1825.

Friedrich Wilhelm died on 17 February 1831 at Gottorp Castle at the age of 46. His descendants include notable figures such as his eldest son Karl, who succeeded him as Duke of Glücksburg, and his fourth son Christian IX, who became King of Denmark in 1863. Friedrich Wilhelm's marriage and progeny established the House of Glücksburg, which has provided royal connections across Denmark, Greece, Norway, and the Commonwealth realms.

His honors included the Grand Cross of the Dannebrog, awarded on 15 January 1811; the Knight of the Elephant, received on 19 December 1811; and the Cross of Honour of the Order of the Dannebrog, also awarded on 19 December 1811.