About Frederik IX of Denmark
Frederik IX (Christian Frederik Franz Michael Carl Valdemar Georg; 11 March 1899 – 14 January 1972) was King of Denmark from 1947 to 1972. Frederik was born into the House of Glücksburg during the reign of his great-grandfather King Christian IX. He was the first child of Prince Christian of Denmark and Princess Alexandrine of Mecklenburg-Schwerin (later King Christian X and Queen Alexandrine). 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 married Princess Ingrid of Sweden. They had three daughters: Margrethe, Benedikte and Anne-Marie. During Nazi Germany's occupation of Denmark, Frederik acted as regent from 1942 until 1943 on behalf of his father, who had suffered a horseback riding accident in October 1942. Frederik became king on his father's death in April 1947. During Frederik's reign, Danish society changed rapidly, the welfare state was expanded and, as a consequence of the booming economy of the 1960s, women entered the labour market. The modernization brought new demands on the monarchy and Frederik's role as a constitutional monarch. Frederik died in 1972, and was succeeded by his eldest daughter, Margrethe II. Frederik's father became crown prince, and Frederik moved up to second in line to the throne. Frederik himself became crown prince.
Biography source: Wikipedia. The profile adds birthday-specific historical context from the Celebs Birthday Today editorial database.