The title Duke of Ayen (duc d'Ayen) was created by King Louis XV on 12 March 1737 raising the former county of Ayen to a Dukedom. [1] It was used as a courtesy title by the eldest son of the Duke of Noailles. [2] The lineage of Dukes of Ayen are cousins to the Dukes of Mouchy, [3] a cadet branch [4] of the House of Noailles. [3]