Margrethe II (Danish: [mɑˈkʁeˀtə]; Margrethe Alexandrine Þórhildur Ingrid, born 16 April 1940) is Queen of Denmark and commander-in-chief of Danish Defence. Born into the House of Glücksburg, a royal house with origins in northern Germany, she is the eldest child of Frederick IX of Denmark and Ingrid of Sweden. She became heir presumptive to her father in 1953, when a constitutional amendment allowed women to inherit the throne. Margrethe succeeded her father upon his death on 14 January 1972. On her accession, she became the first female monarch of Denmark since Margrethe I, ruler of the Scandinavian kingdoms in 1375–1412 during the Kalmar Union. In 1967, she married Henri de Laborde de Monpezat, with whom she had two sons: Crown Prince Frederik and Prince Joachim.