Part of a resistance network
No sooner had Jeanne reached the peak of her powers than her career was curtailed by the outbreak of the First World War. Whereas her life had to this point been taken up with tournaments and family engagements, she decided to leave the courts behind her and volunteer as a Red Cross nurse.
After spending four years at the front, during which time she became a head nurse, Jeanne returned to Paris on suffering serious wounds to her right arm, which would prevent her from holding a racquet and playing tennis again. She had, in any case, decided to devote her life to helping others and lived out her principles by playing an active role in the Second World War, forming part of a resistance network in which she had the task of relaying messages.
Caught and tortured by the Gestapo, Jeanne refused to give her captors any information and was sent to a concentration camp in Germany. Though she survived the ordeal, the ill treatment she suffered during her internment left her much weakened.