House of Glücksburg
Born into the House of Glücksburg, Frederick was the elder son of King Christian X and Queen Alexandrine of Denmark. He became crown prince when his father succeeded as king in 1912. As a young man, he was educated at the Royal Danish Naval Academy. In 1935, he was married to Princess Ingrid of Sweden and they had three daughters, Margrethe, Benedikte and Anne-Marie. During Nazi Germany's occupation of Denmark, Frederick acted as regent on behalf of his father from 1942 until 1943.