Agnès de La Barre de Nanteuil, the first daughter of Gabriel de La Barre de Nanteuil and wife Sabine Cochin, was born on 17 September 1922 at Neuilly-sur-Seine.

She grew up in Paris and Bretagne, at the Runiac castle. Upon completing studies, she became a teacher of English, and a social medical worker. Motivated by her Christian faith, she became the cub mistress in the guides of France, and a member of the Catholic movement. 

At the time the World War II broke out, Agnès was seven. Under occupied France, Gabriel de la Barre de Nanteuil, alongside his wife, joined the Resistance. Having ardently espoused the cause, Agnès notably helped in the extraction of about thirty Allied fly boys to England, also serving as a liaison officer in the underground Army, getting false documents for STO draft-dodgers, and, in 1944, marked out with beacons an area for dropping Maquis equipment.

On 13 March 1944, having been denounced, Agnès was arrested by the Germans and handed over to the Rennes Gestapo, where for several days she endured the torture, thereby enabling her friends to flee. 

Injured when the train transporting her to Germany came under air attack, she died shortly afterwards from her injury, at the Paray le Monial train station, on 13 August 1944. She was twenty two. Before breathing her last, she murmured a few words for her family: 
 “I am dying for my God and my fatherland…
I was betrayed, but I have forgiven…”

Agnès, posthumously awarded the Resistance Medal by General de Gaulle, was made Knight of the Legion of Honour. The 26th 2002-2003 batch of École militaire de Saint-Cyr Coëtquidan was named in her honour. Jeanne d'Arc was the only woman before her to have had her name given to a batch of this prestigious officers’ academy.

Commendation in the order of the 11th Region
in honour of Agnès de La Barre de Nanteuil
Who died for France.

“Secretary and liaison officer of the Morbihan departmental command,
Agnès de La Barre de Nanteuil undertook highly risky go-between missions.
Denounced and tortured by the Gestapo, she heroically kept her mouth shut.
Killed as she was being transported to Germany,
she exhibited exemplary patriotic
which forever shall remain in the mind of
her FFI and FTP comrades.”