Marie Clotilde of France ( 23 September 1759 -- 7 March 1802 ) was Queen of Sardinia as wife of Charles Emmanuel IV . Marie Clotilde of France ( Marie AdÃ laÃ de Clotilde XaviÃ re ; 23 September 1759 -- 7 March 1802 ) , known as Madame Clotilde , was a French princess who became Queen of Sardinia as Clotilda in 1796 . She was the younger sister of Louis XVI of France and later the wife of Charles Emmanuel IV of Sardinia .