[citation needed] During World War II, Gilou served as a naval officer, and in 1940 joined General de Gaulle and the "France Libre" on a staff mission.
In 1942 he enlisted in the FNFL (Flotte Nationale de la France Libre, the French Resistance Navy), where he became an Officer Interpreter for the Cipher Services (ORIC).
[1][2] In 1945, Pierre Lazareff, Chief Editor of the daily France-Soir, decided to foster the creation of a new monthly news magazine, Réalités, with its first issue dated February 1946.
The photographers he hired included Edouard Boubat, Henri Cartier-Bresson, Robert Capa, David Seymour, Werner Bischof, Bruce Davidson, Dennis Stock, Eugene Smith, Robert Doisneau, Brassaï, Manuel Alvarez Bravo, William Klein, Irving Penn, and Richard Avedon.
In this line, he began giving lectures and courses at the Institut Supérieur des Beaux-Arts of Besançon (Doubs, France) in 1958.