9 May 1949

Rainier III becomes Prince of Monaco.

Prince Rainier III ruled the Principality of Monaco for almost 56 years, making him one of the longest ruling monarchs in European history. Though internationally known for his marriage to American actress Grace Kelly, he was also responsible for reforms to Monaco’s constitution and for expanding the principality’s economy from its traditional casino gambling base to its current tax haven role. Gambling accounts for only approximately three percent of the nation’s annual revenue today; when Rainier ascended the throne in 1949, it accounted for more than 95 percent.

Rainier was born at Prince’s Palace in Monaco, the only son of Princess Charlotte, Duchess of Valentinois, and her husband, Prince Pierre, Duke of Valentinois. Rainier was the first native-born prince since Honoré IV in 1758. Rainier’s mother was the only child of Louis II, Prince of Monaco, and Marie Juliette Louvet; she was legitimized through formal adoption and subsequently named heir presumptive to the throne of Monaco. Rainier’s father was a half-French, half-Mexican who adopted his wife’s dynasty, Grimaldi, upon marriage and was made a Prince of Monaco by marriage by Prince Louis, his father-in-law. Rainier had one sibling, Princess Antoinette, Baroness of Massy.

Rainier’s early education was conducted in England, at the prestigious public schools of Summerfields in St Leonards-on-Sea, Sussex, and later at Stowe, in Buckinghamshire. After England, Rainier attended the Institut Le Rosey in Rolle and Gstaad, Switzerland from 1939, before continuing to the University of Montpellier in France, where he obtained a Bachelor of Arts degree in 1943, and finally to the Institut d’études politiques de Paris in Paris.

In 1944, upon his 21st birthday, Rainier’s mother renounced her right to the Monegasque throne and Rainier became Prince Louis’s direct heir. In World War II Rainier joined the Free French Army in September 1944, and serving under General de Monsabert as a second lieutenant, and seeing action during the German counter-offensive in Alsace. He received the French Croix de Guerre with bronze star and was given the rank of Chevalier in the French Legion of Honor in 1947. Following his decommission from the French Army, he was promoted by the French government as a captain in April 1949 and a colonel in December 1954.

In the 1940s and 1950s, Rainier had a ten-year relationship with the French film actress Gisèle Pascal, whom he had met while a student at Montpellier University, and the couple lived at Saint-Jean-Cap-Ferrat. Rainier’s sister, Princess Antoinette, wishing her own son to ascend the throne, spread rumours that Pascal was infertile. The rumours combined with a snobbery over Pascal’s family origins ultimately ended the relationship.

Rainier became the Sovereign Prince of Monaco on the death of Louis II on 9 May 1949.