Clément Moreau was born Carl Meffert in Koblenz (Germany) in 1903. Due to his political activism he had to leave Europe. In Buenos Aires, he was well integrated into the artistic milieu. He published his caricatures in many German –and Spanish– language publications.
From his native Koblenz, Moreau moved to Berlin where he worked as a graphic artist for left-wing publishers from 1926. There he met artists such as Käthe Kollwitz with whom he formed a deep friendship. In 1933, Moreau was forced to flee to Switzerland. He stayed at the Z-Haus in Zurich, a house that hosted emigrants, and there met his future wife, Nelly Guggenbühl. His continued political activism, conducted through Vorwärts, a journal based in Basel, obliged him to change his name to avoid being sent back to Germany. His choice of name –Clément Moreau– used  the same initials with which he already signed his work. But danger still lurked. With the help of Guggenbühl's family, he obtained a passport and in 1935 sailed from the port of Marseille to Buenos Aires. His wife followed soon after. Once in Argentina, he started to teach drawing at the Cangallo and Pestalozzi schools. In the same year, 1935, he became a member of the Argentine AIAPE group and worked as a political caricaturist for several magazines: German-language journals as well as Argentinian ones, such as Argentinisches Tageblatt, Crítica, La Vanguardia, Noticias Gráficas, Fastrás, Argentina Libre and Nervio. Until he was able to master Spanish, his drawings filled the void created by his inability to write in that language. In 1937, he was one of the founders of the Das Andere Deutschland (The Other Germany) aid organisation. He produced satirical works about Hitler in a series of engravings titled La comedia humana (The Human Comedy). In 1938, he founded a theatre group, which he called Truppe 38. In 1962,  Moreau and Guggenbühl travelled to Zurich looking for professors to teach at the Universidad de Resistencia (Chaco, Argentina) where Clément Moreau had previously taught. A military coup in Argentina convinced them to stay in Zurich for good.