The papacy of Pius XII was marked by diplomatic balances. As Vatican Secretary of State under his predecessor, Pacelli witnessed the dire consequences of the "Mit brennender Sorge" against the Nazi regime. His work on behalf of persecuted communities was indirect but effective.
The Nazis occupied Rome for nine months between 1943 and 1944. At that time, some 12,000 Jews lived in Rome. Of these, about 10,000 managed to survive by hiding in various places in the city, including more than 150 convents and religious institutions.