[1] After Benito Mussolini became Prime Minister of Italy Barontini lost his job due to his anti-fascist convictions and faced political persecution.

[3] In 1931 he went in exile in France, and two years later moved to the Soviet Union, where he worked as a technician and attended classes at the International Lenin School,[1] an institution which trained Communist cadres, and the Frunze Military Academy.

He took part in the defense of Madrid and, in January 1937, replaced Antonio Roasio as political commissar of the Garibaldi Battalion, a unit consisting of Italian volunteers.

[5] After the German invasion he was interned in Le Vernet until the Soviet government, which was still cooperating with the Axis at the time, claimed him as his citizen and requested his release.

[1] Once released Barontini worked with the FTP-MOI in Marseilles area,[6] which he organized among Italian emigrants, and the GAP and the Garibaldi Brigades (of which he was regional commander in Emilia-Romagna) in Italy.