Rainier III, Prince of Monaco Rainier III, Prince of Monaco Rainier III (Rainier Louis Henri Maxence Bertrand Grimaldi; 31 May 1923 – 6 April 2005) 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 beyond its traditional casino gambling base. 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
Louis II, Prince of Monaco unhappy with her husband. Shortly thereafter, she left the country permanently, and the princely couple's marriage was annulled in 1880. Louis was raised in Germany by his mother and stepfather, Count (later Prince) Tassilo Festetics von Tolna, along with his eldest half-sister, Maria-Mathilde (later grandmother of Princess Ira von Fürstenberg), and did not see his father until age 11 when he was obliged to return to Monaco to be trained for his future princely duties. Louis' father, Prince Albert I, was a dominating personality who had made Monaco a center of cultural activity and whose intellectual achievements were recognized around