During World War II, she was a member of the French Resistance and orchestrated her husband's release from Buchenwald concentration camp after he was captured by the Gestapo.

[1] She was one of the first two women to be admitted to the Ecole des Sciences Politiques[2] and studied piano at École du Louvre.

They managed to establish a system of communication with Parisian inmates and relayed information to families of prisoners in secret detention facilities.

Their system led to the creation of the Comité des œuvres sociales de la Résistance (COSOR).

She later learned that her husband was imprisoned at the Buchenwald concentration camp and arranged to meet the head of the Gestapo in Metz.

[1] Following France's liberation, Lefaucheux was elected to the Constituent Assembly of the Provisional Government of the French Republic,[4] representing the Organisation Civile et Militaire.

[1] Lefaucheux was a founder of the Association des Femmes de l'Union Française, which was concerned with the welfare of Algerians and Africans.

Her husband died in a car accident in 1955, and following his death, she became France's Representative to the Commission on the Status of Women of the United Nations, one of the committees of the Economic and Social Council, where she assumed the presidency.