Margrethe II is the queen of Denmark, as well as the supreme authority of the Church of Denmark and Commander-in-Chief of the Danish Defence. On her accession in January of 1972, Margrethe became the first female monarch of Denmark since her namesake, Margrethe I, ruler of the Scandinavian kingdoms from 1375 to 1412. She is also the second-longest-reigning Danish monarch after her ancestor, Christian IV. Margrethe is currently 78 years old, and her heir apparent is her oldest son, Frederik, Crown Prince of Denmark.