After fighting a duel against the Comte de Pontgibaud, he killed the Marquis de Portes in 1625.[2] Dueling had long been forbidden, but the penalty of death was rarely enforced. Cardinal Richelieu, who believed the severity of the penalty contributed to its lack of enforcement, argued for its liberalization. An edict of February 1626 restricted the death penalty to duels in which one of the participants died, or the seconds also dueled. It was registered by parlement on 24 March.[3] Montmorency-Bouteville dueled and killed Jacques de Matignon, Comte de Thorigny, on 25 March.[4] He injured the Baron de la Frette in 1627,[5] then fled to Brussels to escape the wrath of Louis XIII. Eventually Louis XIII let it be known that Montmorency-Bouteville could return to France, but not to Paris or the court.[3]
François d'Harcourt Beuvron, a relative of Thorigny, was determined to avenge Thorigny's death. At the insistence of Louis XIII, a dinner of reconciliation was arranged in Brussels, but failed, and afterward Beuvron issued a challenge. On 12 May 1627 at the Place Royale in Paris, Montmorency-Bouteville dueled Beuvron without fatality, but Montmorency-Bouteville's second, François de Rosmadec, Comte de Chappelles, dueled and killed Beuvron's second, the Marquis de Bussi d'Amboise. While Beuvron took refuge in England, Montmorency-Bouteville and Rosmadec, despite their nobility, were beheaded at the Place de Grève in Paris on 22 June 1627.[6]