Frederick IX was the King of Denmark from 1947 until his death in 1972. He was born on March 11, 1899, and was the son of King Christian X. Frederick IX played a significant role in modernizing the Danish monarchy and was known for his approachable and friendly demeanor. During his reign, Denmark experienced significant social and economic changes, including the expansion of the welfare state. Frederick IX was also a patron of the arts and supported various cultural initiatives. He was married to Queen Ingrid, and they had three daughters, including Queen Margrethe II, who succeeded him.