 After the outbreak of World War II (1939–45) Amidieu du Clos rejoined the army and was appointed a colonel.During the occupation of France he was chairman of the board of directors of the Société française Krupp.The company was founded on 19 April 1943 by a private act and was given the appearance of a French identity by its "first directors", Amidieu du Clos, Jacques Breil, Émile-Joseph Cuiller and Georges Ramat, auditor.