Princess Marie Melita Of Hohenlohe-Langenburg

Wilhelm Friedrich, Duke of Schleswig-Holstein-Sonderburg-Glücksburg (German: Wilhelm Friedrich Christian Günther Albert Adolf Georg Prinz zu Schleswig-Holstein-Sonderburg-Glücksburg), later known as Duke of Schleswig-Holstein from 1934, was born on 23 August 1891 at Grünholz Castle in Schleswig-Holstein, within the Kingdom of Prussia. He was the fifth child and only son of Friedrich Ferdinand, Duke of Schleswig-Holstein-Sonderburg-Glücksburg, and Princess Karoline Mathilde of Schleswig-Holstein-Sonderburg-Augustenburg.

His paternal grandfather was Friedrich, Duke of Schleswig-Holstein-Sonderburg-Glücksburg, making Wilhelm Friedrich a nephew of Christian IX of Denmark. Following the death of his paternal grandfather in 1885, Wilhelm Friedrich's father succeeded as head of the House of Schleswig-Holstein-Sonderburg-Glücksburg and assumed the title of duke. Wilhelm Friedrich held the dynastic position as the sixth Duke of Schleswig-Holstein and served as the head of the House from 21 January 1934 until his death.

In 1916, Wilhelm Friedrich married Princess Marie Melita of Hohenlohe-Langenburg, who was the daughter of Ernst II, Prince of Hohenlohe-Langenburg, and Princess Alexandra of Saxe-Coburg and Gotha. The marriage took place on 5 February 1916 in Coburg. The couple had four children: Hans Albrecht, Hereditary Prince of Schleswig-Holstein; Prince Wilhelm Alfred Ferdinand of Schleswig-Holstein-Sonderburg-Glücksburg; Friedrich Ernst Peter, who later became the seventh Duke of Schleswig-Holstein; and Princess Marie Alexandra of Schleswig-Holstein-Sonderburg-Glücksburg.

Hans Albrecht, born on 12 May 1917, was designated as the Hereditary Prince but died on 10 August 1944. Prince Wilhelm Alfred Ferdinand was born on 24 September 1919 and died on 17 June 1926. Friedrich Ernst Peter, born on 30 April 1922, succeeded Wilhelm Friedrich as the seventh Duke of Schleswig-Holstein and married Princess Marie Alix of Schaumburg-Lippe; he died on 30 September 1980. Princess Marie Alexandra was born on 9 July 1927 and married Douglas Barton-Miller on 27 July 1970.

In the line of succession and family events, Wilhelm Friedrich’s family lines intersected with various noble houses, including Saxe-Coburg and Gotha and Schaumburg-Lippe.

Following the death of Albert, Duke of Schleswig-Holstein, the head of the House of Schleswig-Holstein-Sonderburg-Augustenburg, on 27 April 1931, Wilhelm Friedrich's father, Friedrich Ferdinand, became head of the House of Oldenburg and inherited the title of Duke of Schleswig-Holstein. Upon the death of Friedrich Ferdinand on 21 January 1934, Wilhelm Friedrich succeeded as the head of the House of Schleswig-Holstein-Sonderburg-Glücksburg.

Wilhelm Friedrich died on 10 February 1965 in Coburg, Bavaria, West Germany.