He was appointed an officer in charge of the regiment of Conti and, in 1734, succeeded his father as governor of Bapaume. The lordship of d'Estissac originally belonged to the Dukes of Aquitaine, 
then to the English, and then to the French crown. It came into the de La Rochefoucauld family through marriage with Claude, Dame d'Estissac. 
On 24 October 1737, Louis XV, King of France, officially certified Louis Francois Armand as Duc d'Estissac. Then, in August 1758, he was made a hereditary Duc by letters patent. 
On 18 November 1737 he married Marie de La Rochefoucauld and they became the parents of four children. He gave his son's education as reason for taking him travelling whilst still young, as this enabled him to leave the Court which he had never really liked. At the same time he took advantage of this absence to administer his possessions and his Duchy, where he quickly made himself known to the inhabitants. 
On 1 February 1749 he became a Knight Commander of the Order of the Holy Spirit and of the orders of the king. On the death of his cousin, who was also his father-in-law, he became the head of the family de La Rochefoucauld, receiving its titles and armorial bearings. In 1767 King Louis XV created him Marquis de Maignelay. He died in Paris on 28 May 1783.

Source: Leo van de Pas