Giulio Marconi was the only son of Guglielmo and Beatrice Marconi. He grew up and lived like his sisters in England and Italy following his parents' wanderings from one country to the other. He attended the Italian Naval Academy in Livorno and served in the Italian Navy during World War II. He attained the rank of Capitano di Corvetta. After the war he served as President of the Italian Marconi Co. and the Societa' Marittima Italiana until his retirement. Giulio died in Rome in 1971.