Charlotte was created Duchess of Valentinois by Albert I on 20 May 1919, and on 1 August 1922, following Louis II's accession on 26 June of that year, she was officially designated the Hereditary Princess of Monaco as her father's heir presumptive. In 1920 she married comte Pierre de Polignac, who belonged to a junior branch of a prominent French ducal family. Prior to the wedding, a Monégasque ordinance of 18 March 1920 had changed Pierre's name and coat of arms to those of "Grimaldi". On 20 March, he was allowed to take the title of Duke of Valentinois (his French prefix of "comte" was, in fact, a courtesy title). Princess Charlotte, Duchess of Valentinois and Pierre Grimaldi had a daughter, Princess Antoinette, baroness de Massy, and then a son, Rainier, marquis des Baux.