On 10 January 1747 Louis was married by proxy at Dresden to Maria Josepha of Saxony , the fifteen year old younger daughter of Frederick Augustus II , Prince-Elector of Saxony and King of Poland and his wife , Archduchess Maria Josepha of Austria . On 10 January 1747 Louis was married by proxy at Dresden to Maria Josepha of Saxony , the fifteen-year-old younger daughter of Frederick Augustus II , Prince-Elector of Saxony and King of Poland and his wife , Archduchess Maria Josepha of Austria .