Rainier III (rĕnyāˈ) [key], 1923–2005, prince of Monaco (1949–2005), a member of the Grimaldi family, which has ruled the tiny principality since 1297. Fiercely anti-Nazi, Ranier served with distinction as an officer in the French Army during World War II. On the death of his grandfather, Louis II, in 1949 he succeeded as ruler of Monaco. Rainier devoted himself to insuring Monaco's independence and financial stability, transforming a state that had been economically devastated by the war into an international business center, a successful resort for the wealthy, and a modern tourist destination. In 1956 he married the American actress Grace Kelly (see Grace, princess consort of Monaco). His son, Albert II, succeeded him.