Julius Rosenbaum was born into a Jewish family in Neuenbürg, Germany on 9 July 1879. In 1900, he spent a year in Paris studying at the Académie Julian, during a period when Henri Matisse, a former pupil, also returned to make use of the live models. Afterwards, Rosenbaum continued his studies at the Akademie der bildenden Künste in Munich (1901–5), in Breslau (1905–10) and Berlin under Lovis Corinth (1911–15), also attending the State Art School in Weimar and Berlin-Schöneberg. During the First World War he served with the German Army, then worked as a cartoonist for newspapers including 'ULK'. During the 1920s he became an exhibiting member of the Berlin Secession and set up artists' associations in Weimar and Berlin. In 1930 he married fellow artist Adèle Reifenberg (1893–1986). Each had a work included in the 'Exhibition of German-Jewish Artists' Work: Painting, Sculpture, Architecture' (5-15 June 1934) organised at the Parsons Gallery, London by German-Jewish emigre dealer, Carl Braunschweig (later Charles Brunswick), which included in total 221 artworks by 86 artists suffering persecution under the Nazi regime. Prior to migration, when banned from painting due to anti-Semitic legislation, he established the Jewish Artists’ Aid Organisation and taught crafts at Jewish boys’ schools. The couple fled to London in 1939, where exhibiting opportunities were limited during the war but he did exhibit two works including a coloured drawing entitled 'Departure of Jews from Berlin for Palestine' at the Ben Uri summer exhibition in 1944, while chiefly earning a living repairing Blitz-damaged houses and restoring china during the war. Postwar, between 1948 and 1956, the couple established a successful painting school, exhibiting alongside their pupils as the 'Belsize Group' and had a joint exhibition with Ruth Collet at Ben Uri's Portman Street Gallery in 1950. Julius Rosenbaum died in The Hague, Netherlands, on a visit to see a Rembrandt exhibition on 24 August 1956, and was buried in England.