| Conflict: | Battle of Castelnaudary |
| Date: | 1 September 1632 |
| Place: | Castelnaudary, Occitanie |
| Result: | French Royalist victory |
| Combatant2: | French rebels following Gaston, Duke of Orléans, brother of Louis XIII |
| Commander1: | Henri de Schomberg |
| Commander2: | Henri II de Montmorency Achille d'Étampes de Valençay |
The Battle of Castelnaudary occurred at Castelnaudary, France, on 1 September 1632, between the rebel forces of Henri II de Montmorency (loyal to Gaston, Duke of Orléans) and the royalist forces of Marshal Henri de Schomberg (loyal to King Louis XIII).
Duke Henri II de Montmorency was solicited by Gaston, Duke of Orléans (brother of King Louis XIII) to launch a rebellion against the king's Chief Minister, Cardinal Richelieu. Using his position as Governor of Languedoc, he raised levies of troops and money and took command of an army of six or seven thousand troops. His force included a number of commanders who had previously served under him at the Battle of Avigliana including Brigadier Achille d'Étampes de Valençay.
Richelieu's representatives tried in vain to negotiate with the Duke and when discussion failed, Richelieu sent Henri de Schomberg and a force of royalist troops to confront him.
The battle took place at Castelnaudary in the Languedoc-Roussillon region of France, on 1 September 1632. Government forces defeated the rebels commanded by Montmorency and took him prisoner.
Trying to emulate his victory at Avigliana in 1630, Montmorency lead a charge into the royal camp at the head of a few horsemen, he cut his way through six ranks of infantry amidst a continued shower of shot, and fought against overwhelming numbers, until his horse dropped dead. Severely wounded, he was captured.
The Duke of Orléans abandoned Montmorency by submitting to the will of Richelieu, and Henri II was executed in Toulouse as a traitor on 30 October 1632.