During World War II, Josephine served with the French Red Cross and was an active member of the French resistance movement. The French Resistance was a group of individuals who helped to win the war against the German Nazis enemy with undercover work. Using her career as a cover Baker became an intelligence agent, carrying secret messages written in invisible ink on her sheet music. She was awarded honor of the Croix de Guerre, and received a Medal of the Resistance in 1946. In 1961 she received the highest French honor, the Legion d’Honneur from French president Charles deGaulle.