In 1744, at the age of nineteen, Penthièvre married Princess Maria Teresa d'Este (1726-1754), the daughter of Francesco III d'Este, the sovereign Duke of Modena and Reggio, and his first cousin, Charlotte Aglaé d'Orléans. The young couple occupied a suite of apartments at Versailles which had previously been occupied by their joint ancestor Madame de Montespan. These apartments were used by the duke and his family until the reign of Louis XVI of France when the space was given to "Mesdames", the new king's spinster aunts, Louis XV's unmarried daughters.