Jean was Grand Duke of Luxembourg for nearly four decades in the 20th Century.

He was born on Jan. 5, 1921, in Berg Castle, in Colmar-Berg. His mother was Grand Duchess Charlotte, and his father was Prince Felix of Bourbon-Parma. He was their oldest child.

Young Jean went to school initially in his home country and then in the U.K., at Ampleforth College.

When Germany invaded Luxembourg on May 9, 1940, Charlotte and her government leaders set up a government in exile in France and then, after the fall of that country, moved to Portugal. Charlotte ended up in London, from where she used radio broadcasts to encourage her people to keep the faith. She later traveled to Canada and the United States.

Charlotte had married Prince Felix of Bourbon-Parma on Nov. 6, 1919. They had six children: Jean (1921), Elizabeth (1922), Marie Adelaide (1924), Marie Gabrielle (1925), Charles (1927), and Alix (1929). Those children went with their family across the Atlantic and continued their studies in Montreal during the war. Jean, the oldest child, initially studied at a university in Quebec City and later volunteered for the Irish Guards. He was part of the D-Day landings, fighting in the Battle for Caen and helping liberate Brussels, Belgium. He helped Allied troops liberate his home country, in September 1944, and then kept on fighting, helping the Allied troops invade and then defeat Germany. He remained in the British Army for two years after the end of the war.

On April 9, 1953, Jean married Princess Joséphine-Charlotte of Belgium. They had five children: Marie-Astrid (1954), Henri (1955), Jean (1957), Margaretha (1957), and Guilaume (1963).

Charlotte gradually delegated most of her ducal duties to her son, Jean, who had returned home after the war. On Nov. 12, 1964, when she was 68, she abdicated; at that point, Jean became Grand Duke. He continued his mother's goal of a deeper cooperation between European nations. Most prominently, he helped facilitate Luxembourg's joining of the European Union, in 1992.

Jean presided over a period of great prosperity in his country, and he and his family were popular with the people at large. This was the case when he stepped down, on Oct. 7, 2000. His oldest son became Grand Duke Henri.

The former grand duke and his wife, Josࢹphine-Charlotte, retired to Fischbach Castle. She died in 2005. He died in 2019. He was 98 and, at that time, was the world's oldest living monarch.