Prince Knud was born on 27 July 1900 at Sorgenfri Palace in Kongens Lyngby north of Copenhagen during the reign of his great-grandfather, King Christian IX. His parents were Christian of Denmark, son of the heir apparent Frederick, and Alexandrine of Mecklenburg-Schwerin. Knud's only sibling, Frederick, had been born one year before him. Christian IX died on 29 January 1906, and Knud's grandfather succeeded him as Frederick VIII. Six years later, on 14 May 1912, Frederick VIII died, and Knud's father ascended the throne as Christian X. As was customary for princes at that time, Knud started a military education and entered the naval college. He married his first cousin, Princess Caroline-Mathilde of Denmark, on 8 September 1933 at Fredensborg Palace. She was a daughter of Frederick VIII's son Harald. Knud and Caroline-Mathilde had three children: Princess Elisabeth, Prince Ingolf and Prince Christian.
Heir presumptive
On 20 April 1947, Christian X died, and Knud's brother Frederick succeeded to the throne as Frederick IX. Since Frederick IX had fathered no sons and the Danish Act of Succession at the time followed the principle of agnatic primogeniture, Prince Knud became heir presumptive and next in line to succeed his brother as king. Prince Knud called the electorate "a shower of bastards" for voting for the change. Frederick IX had, however, fathered three daughters. In 1953, the Danish Act of Succession was amended to follow the principle of male-preference primogeniture. The new law made Frederick IX's thirteen-year-old daughter Margrethe the new heir presumptive, placing her and her two sisters before Knud and his family in the line of succession.
Later life and legacy
King Frederick IX died in 1972 and was succeeded by his daughter Queen Margrethe II. Prince Knud died in Gentofte on 14 June 1976. He was buried at Roskilde Cathedral. His widow died on 12 December 1995. In 1953 a students home in Copenhagen was named "Arveprins Knuds Kollegium" in honor of Prince Knud. At the time, Prince Knud was protector of Sydslesvigsk Studie- og Hjælpefond,, an area that could be considered the birthplace of the House of Schleswig-Holstein-Sonderburg-Glücksburg, the royal family Knud was a part of. The Princess Caroline-Mathilde Alps in Greenland were named by the 1938–39 Mørkefjord Expedition in his wife's honour for Prince Knud had been the patron of the expedition.
Issue
Princess Elisabeth Caroline-Mathilde Alexandrine Helena Olga Thyra Feodora Estrid Margarethe Désirée
Prince Ingolf Christian Frederik Knud Harald Gorm Gustav Viggo Valdemar Aage of Denmark. Lost his title and became Count Ingolf of Rosenborg after marrying without royal consent to Inge Terney. He has no issue.
Prince Christian Frederik Franz Knud Harald Carl Oluf Gustav Georg Erik of Denmark. Lost his title and became Count Christian of Rosenborg after marrying without consent to Anne Dorte Maltoft-Nielsen. He had three daughters, Countess Josephine, Countess Camilla, and Countess Feodora.