Prince William was born in
Biebrich on
Christmas Eve in 1787, the son of
Prince Frederick of Hesse-Kassel and
Princess Caroline of Nassau-Usingen. His father was himself a younger son of
Frederick II, Landgrave of Hesse-Kassel and
Princess Mary of Great Britain. Prince William lived most of his life in Denmark where he had several posts in the Danish military. He was military governor of Copenhagen from 1834 until 1848. He lived for many years in
Prince William Mansion, Copenhagen and afterwards in
Brockdorff's Palace part of
Amalienborg Palace, the official residence for the Danish royal family. As a summer residence the family used
Charlottenlund Palace outside of Copenhagen. Besides his Danish residences, he also had part ownership of the family castle,
Rumpenheim Castle. The castle served as a meeting place for the Hesse-Kassel-Rumpenheim branch for many years and gathered Danish, Hesse, British and other royal families. Landgrave William took a keen interest in Danish affairs of state and in the succession issues in the 1840-ties. He and his wife Charlotte were among the leading figures in Denmark, especially after his brother-in-law,
Christian VIII of Denmark became king in 1839. Landgrave William was known for his ultra-conservatism, but also for his hospitality, honesty, loyalty, and generosity. He died in 1867 in Copenhagen, the year after Hesse-Kassel was annexed to
Prussia. He was buried at
Rumpenheim Castle. ==Marriage and children==