He was the son of Gaspard, marquis d'Ossun (1675–1721) and Marie Charlotte de Pas (1689–1759). In 1744-1745 he was a Capitain-lieutenant in the
Cavalerie de la Gendarmerie. Promoted to brigadier in 1747, he would become a
maréchal de camp in 1761. In 1751 he entered the diplomatic corps to become the French ambassador to the
Kingdom of the Two Sicilies. From 1759 to 1777, d'Ossun was French ambassador in Madrid. His appointment as Ambassador in Madrid coincided with the death of King
Ferdinand VI of Spain and the ascension to the throne of King
Charles III of Spain, who was until
King of the Two Sicilies. It was in fact at the request of Charles III, who appreciated d'Ossun as Ambassador in the Two Sicilies, that d'Ossun followed him to Madrid. In Madrid, d'Ossun played an important role in the conclusion of the 3rd
Pacte de Famille between France and Spain, which led to Spain participating in the
Seven Years' War. During his 18 years stay in Madrid, he became a
Grandee of Spain and received the
Order of the Golden Fleece. After his return to France, Louis XVI appointed him in 1778 minister in the Council of State, and awarded him the
Order of the Holy Spirit.
Marriage and children d'Ossun married 3 times. All his wives died very young. Only his third wife Louise Thérèse Hocquart delivered a son : • Charles Pierre Hyacinthe d'Ossun (1750–1790) who married
Geneviève de Gramont,
Première dame d'honneur to Queen Marie Antoinette. ==References ==