Monaco succession crisis of 1918 of this event, pursuant to the clauses of the treaty of 17 July 1918." The French government at the time was still the Vichy regime. Louis II died on 9 May 1949. The Principality of Monaco passed to his grandson, Rainier III. In the absence of an heir male, the ducal titles of Valentinois and Estouteville became extinct in French nobiliary law. Before Rainier III married Grace Kelly in April 1956, he notified the French government of his plans; the French ministry of foreign affairs replied with a message of official congratulations. Count Louis de Causans is suing the French
Honoré IV, Prince of Monaco Honoré IV married Louise Félicité Victoire d'Aumont, Duchess of Aumont, Duchess Mazarin and of La Meilleraye on 15 July 1777 in Paris. They divorced in 1798. They had two sons: During the French occupation of Monaco, Honoré IV was imprisoned for several years. Illnesses resulting from this imprisonment incapacitated Honoré IV in his later years, and following the re-establishment of the Principality a regency was established to rule in Honoré's name. This regency was directed, first, by his brother Joseph Grimaldi, then from 1815 by his son, the Hereditary Prince Honoré who succeeded him in 1819 as Sovereign Prince Honoré