 In September 1915, assigned to the intelligence service established in an island in the Levantine Mediterranean, he organized a network covering the entire Levant.He continued to lead this mission as of August 1916, as second in command of aviso "Laborieux", then at Kastelórizo on the coast of Anatolia.Second in command of submarine in September 1917, he participated in campaigns in the Adriatic until the end of the war.