Honoré d’Estienne d’Orves studied at l’X before becoming known as a hero during the Second World War. After completing his education, he joined the Navy, trained on board the cruiser Joan of Arc and travelled the world. At the outbreak of the war, he was assigned as a lieutenant to the cruiser Duquesne, at the headquarters of the Force X Navy squadron in the eastern Mediterranean. After the Armistice, d’Estienne d’Orves chose the Resistance and joined General de Gaulle in London in September 1940. He adopted the pseudonym "Châteauvieux" and held positions as Head of the 2nd Office of the General Staff of the Free French Forces, Head of Intelligence, and Lieutenant Commander in the Navy of the Free French Forces. Under cover, he set sail for the coast of Brittany in December 1940. This co-founder of Nemrod, one of the first intelligence networks in France, was arrested in Nantes by the Gestapo and executed on August 29, 1941, at the Fort Mont-Valérien. Shortly before, he wrote to his family: "Do not harbor hatred for anyone because of me; everyone has done their duty to their own country. Instead, get to know and better understand the character of France’s neighboring peoples."