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. 21st century legal challenge Count Louis de Causans is suing the French government for US$401 million alleging that France used a "sleight of hand" to deprive Duke Wilhelm II, his ancestor, of the Monegascan throne when it passed the 1911 law permitting Charlotte to be considered a Grimaldi. "A German reign over Monaco, on the eve of the First World War was simply unacceptable for France" said the count’s lawyer, Jean-Marc Descoubès, missing the point that this was never likely; Prince Louis' legitimacy was not questioned by the von Urachs and lasted until 1949. References Further reading Joseph Valynseele Rainier III: est-il le souverain legitime de Monaco? Recueil de l'Office Genealogique et Heraldique de Belgique, XIII (1964), pp. 191–223. 1918 in Monaco House of Grimaldi Monarchy in Monaco History of Monaco Succession France–Monaco relations