Aage Count of Rosenborg
- Category : 1887-births
- Type : MS
- Profile : 3/5 - Martyr / Heretic
- Definition : Single
- Incarnation Cross : RAX Rulership 2
Danish prince and officer of the French Foreign Legion. He was the eldest child and son of Prince Valdemar of Denmark and Princess Marie d'Orléans.
In 1909 Prince Aage joined the Danish Army, and by 1913 had risen to the rank of lieutenant. During World War I he served as an observer in Italy for a year. Returning home to Denmark he was promoted to captain.
Without the legally required permission of the Danish king, Aage married Matilda Calvi dei conti di Bergolo (Buenos Aires, 17 September 1885 – Copenhagen, 16 October 1949) on 1 February 1914. A few days later, he renounced his place in the line of succession to the Danish throne. Aage and Mathilde had one son before their divorce in 1939.
In 1922, Aage received permission from the King, as required by Danish law, to leave the Danish army in order to join the French Foreign Legion. After negotiations between the Danish and the French governments Prince Aage entered the Foreign Legion with the rank of captain.
He was sent to Morocco as part of the French involvement in the Rif War within a year of service. He received the Croix de Guerre after being shot in the left leg. During his seventeen years in the Foreign Legion Prince Aage attained the rank of lieutenant colonel, and also received France's highest order, the Légion d'honneur.
In 1927 he published the book "A royal adventurer" in English about his time in the Foreign Legion.
Prince Aage died of pleurisy in Taza, Morocco, on 29 February 1940, aged 52.