In 1908, with the rank of lieutenant, he participated in the rescue effort after the Messina earthquake, finding the remains of his fiancée under the rubble in Reggio Calabria.

After participating in the conquest of Libya, he distinguished himself during the First World War, earning four silver and two bronze medals for military valour until he was seriously wounded and captured during the battle of Caporetto.

Simoni was thus one of the founding members of the Institute, along with Italo Balbo, Alessandro Pirzio Biroli, Cesare de Vecchi, Alfredo Guzzoni, Eugenio Casagrande and Giacomo Acerbo.

He was however reported by an informant and arrested at his home by SS soldiers on 23 January 1944, while returning from an important organizational meeting of the Front held in the aftermath of the Allied landing at Anzio.

During his imprisonment, he managed to secretly send out of the prison a piece of paper with a short encrypted message, which, translated, read: "Simone Simoni - cell - twelve - Giuseppe - Ferrari - two.