[1] Montmorency's father was a scion of one of the oldest noble families in France, while his wife was the daughter of an aristocratic French planter in Guadeloupe.

Montmorency went on to seek higher education at Collège du Plessis, where he developed his love for the subject of philosophy and the idea of enlightenment.

However, when Catherine was denied the corresponding rank of dame pour accompagner to the prince's wife, Marie-Joséphine, due to her relatively low birth, Laval resigned his post in Provence's household.

[3] Originally known by the title of Comte de Montmorency-Laval, Mathieu served as an adolescent with his father in the American War of Independence with Lafayette.

[4] Montmorency was the Deputy of Montfort-l'Amaury in the Estates General from 28 March 1789 until 30 September 1791,[5] joining as its youngest member.

Napoleon's army won victories in the War of the Third Coalition against Austria, Prussia, Russia, Britain, and allied states.

[12] French dominance was reaffirmed during the War of the Fourth Coalition, before Napoleon's final defeat at the Battle of Waterloo in 1815.

[14] After the Battle of Waterloo and the final defeat of Napoleon, he was made a peer of France and received the title of Vicomte de Montmorency-Laval.

Known for strong reactionary, ultramontane, and Ultra-royalist views, Felicite became the French Minister of Foreign Affairs under Jean-Baptiste Guillaume Joseph, comte de Villèle in December 1821.

However, he resigned his post in December, being compensated by the title of Duc de Montmorency-Laval and the cross of the Legion of Honour soon after.

The following year, he was named tutor to the six-year-old heir to the throne, the Duc de Bordeaux, but died two months after receiving the appointment.

[7][1] He was discovered seated lifeless at the end of the Good Friday Liturgy in St. Thomas d'Aquin church in the fashionable St. Germain des Près faubourg.

[3] Reportedly, Madame de Staël brought Montmorency out of his depression through writing a series of letters to each other.