1940: l’X sets up a new base in Lyon

Following the Armistice of June 22, 1940, and while the north of France is still under German occupation, École Polytechnique moves to Lyon. The building on the Montagne Sainte Geneviève becomes assigned to the Red Cross. In April 1943, during the German invasion of the "Free Zone", the institution moves back to the Rue Descartes. L’X loses its military status for the entire duration of the conflict, which it regains in September 1944 after the liberation of Paris.