He is most remembered for the collection of exhibits he gave to the Cabinet des Médailles in 1862, and for supporting the exiled Comte de Chambord's claim to the throne of France.

His youthful Grand Tour to Italy was marred by the death of his companion, his cousin Henri de Montmorency-Laval; he returned to join Louis XVIII's garde du corps.

After his first wife's death in 1824, he returned to Italy, consoling himself with researches at the site of Metapontum in the Kingdom of Two Sicilies, which he published, and at the age of twenty-eight was received by the Académie des Inscriptions et Belles-Lettres; his archaeological interests ranged from ancient numismatics and ceramics, the subject of his collections, to recovering the secrets of damscening steel: he received a silver medal for his blades at the Exposition of 1844.

He offered a prize of 8000 livres for the first successful process of photolithography while he was assembling one of the finest contemporary natural history collections in France at his château de Dampierre.

[8] From François Rude Luynes commissioned a sculpture of the king who had founded the fortunes of his family; the Louis XIII as a Child was cast in silver rather than bronze.

He took an active part in the Revolution of 1830, equipping and arming at his own expense a contingent of National Guard, but refused the offer from the July Monarchy of a pairie but consented to be appointed a representative of the Second Republic, 1848–51, where his role was that of an independent, before he withdrew to Dampierre with the rise of Napoleon III.