The family lived in precarious economic conditions due to heavy debts, and all the Petrelli's were forced to leave their home town.

In 1934, the entire family moved to Milan to join their eldest son Carlo, who had left a few years earlier, taking lodgings in a single room.

After the armistice between Italy and the US and UK on 8 September 1943, he joined Mussolini’s Italian Social Republic but after a year's service, he chose to desert.

Some of his photos taken in those days, such as the one of a group of partisans stationed on the rooftops of Milan or the well-known image of three girls marching in the street with rifles on their arms, have gone down in history for having been constructed by posing the protagonists themselves, passers-by or colleagues.

[1] In 1948 he made a famous series of documentary photographs, showing the misery, exclusion and hunger of the people in poverty-stricken village of Africo in the Aspromonte, in Calabria.