Born in Nice, Moreu spent his childhood in Marseille, where his father decorated windows and subsequently managed a cafe. After working in a few small trades, he was hired as a mechanic in the printing shop of "Le Petit Marseillais". Requisitioned on a coast guard ship, Moreu joined the French Resistance in 1940. Although he was suffering from a retinal disease, he still participated in the Liberation of Paris. After World War II, he joined the newspaper "La Marseillaise".