The author focuses on the role of Catholic chaplains accompanying Italian troops on the Eastern Front between 1941 and 1943. It draws on the memoirs, diaries, letters and reports of the chaplains, including direct reports sent by them to the Holy See during the war, which only became available to scholars in March 2020 when the Vatican archives relating to the pontificate of Pius XII (1939–1958) were unsealed. This subject has never been addressed in Russian historiography and has been barely explored in Italian studies. The aim of this article is to analyse the information relayed by chaplains about the territories where the Italian army was deployed, the situation of the local population, including people of different nationalities, the religious situation on the occupied territories, the actions of the armed forces (mainly Italian and German) and the activities of chaplains themselves, including not only the spiritual care of the Italian troops, but also the administration of sacraments and the holding of religious services for the local population. Newly discovered sources make it possible to understand how the chaplains saw life among the local population in the territories occupied by Italian troops, whether the Vatican was aware of the real situation, and to infer what the Vatican tried or intended to do for the apostolic work of the military chaplains in the Soviet Union.