On 14 May 1788, he married his second cousin, Bonne-Charlotte-Renée-Adélaïde de Montmorency-Luxembourg, daughter of :fr:Anne Charles Sigismond de Montmorency-Luxembourg|Anne-Charles-Sigismond, duc de Piney-Luxembourg and head of the senior branch of the Montmorencys, by his wife Madeleine-Suzanne-Adélaïde de Voyer de Paulmy d'Argenson. The Duke and his wife had three children:
Guy-Anne-Marie-Louis-Henri-Adalric, prince de Laval, Huntmaster of Morbihan;
Charlotte-Adélaïde, 2nd Duchess of San Fernando Luis, who married in 1817, :fr:Athanase-Gustave-Charles-Marie de Lévis-Mirepoix|Gustave de Lévis, marquis de Mirepoix: descendants include the historian, Antoine de Lévis-Mirepoix;
Marguerite-Emmanuelle-Pauline married Aimé, marquis de Couronnel: ancestors of the :fr:Famille de Pimodan|Rarécourt family.
Through his wife's family their descendants inherited great wealth, as both her elder brothers died childless and in 1791 her younger sister Marie-Madeleine married Miguel Caetano Álvares Pereira de Melo, 5th Duque de Cadaval, emigrating to Portugal.
Diplomatic career
Upon the outbreak of the French Revolution, after locating remaining family members in Paris, Adrien de Laval fled to England. As a French émigré in London, the marquis became friendly with the Prince of Wales and his circle. During the revolutionary wars his father appointed him as aide-de-camp and despatched him to Italy as a captain in the :fr:Régiment de Montmorency|Montmorency Regiment being stationed at Rome. After the ban on émigrés was lifted in 1800 he returned to France. Adrien de Laval was one of the first to congratulate Louis XVIII at Calais in 1814, and the king promoted him maréchal de camp and bestowed on him the style of Prince de Montmorency-Laval; he succeeded to his father's dukedom in 1817. On 15 August 1814, he was appointed French ambassador to Spain. There he came into conflict with Ceballos. But on receiving news of the return of Napoleon from Elba, a reconciliation was effected and Montmorency-Laval agreed to stay in Madrid, contrary to instructions from the French government. He successfully managed the somewhat tense relations between the Spanish Borbóns and the newly restored French Bourbons, being honoured in 1815 as a knight of the Golden Fleece and made Duke of San Fernando Luis with the rank of grandee. His next ambassadorial posting was to Rome, where he arrived just before the end of Pius VII's reign and was present during the conclave for the election of his successor as pope; he supported the efforts of Austria in favour of Cardinal Castiglioni's candidacy. However, Cardinal Annibale della Genga was elected as Leo XII. On 20 March 1828, the Duc de Laval was appointed French ambassador to Austria. His name was also mooted as a candidate to be king of Greece, but he twice refused King Charles X's proposals. He was then posted as Ambassador to the Court of St James's, returning to Paris just before Charles X's exile. At Talleyrand's request, he dealt with unpleasant issues in London caused by his relatives, Louis, duc de Valençay and his father Edmond, duca di Dino, who had become addicted to gambling. Declining to swear allegiance to King Louis-Philippe, the Duke and Duchess retired to the chateau de Montigny, where they received visitors, including Talleyrand. The Duke died on 16 June 1837 and, having been predeceased by his son at Naples in 1819, his youngest brother Eugène succeeded to his French titles before they became extinct, whereas his Spanish ducado and grandeza devolved upon his elder daughter and her descendants.
