First, he was entrusted to the parish of Cernusco sul Naviglio and then in 1926, the densely populated San Pietro in Sala of Milan, he continued his vocation for years, creating a deep bond with his parishioners.

His fame as an educator came to Cardinal Archbishop of Milan, Alfredo Ildefonso Schuster who, in 1936,[6] appointed him as spiritual director of the Gonzaga Institute of the Brothers of Christian Schools.

"At the end of the 1930s, Gnocchi was named chaplain of the second legion of Milan, composed of students of the Università Cattolica del Sacro Cuore and the Gonzaga Institute.

After the Balkans Campaign in 1941, in 1942 Gnocchi left for the Russian front as chaplain of the 2nd Alpine Division Tridentina, where he participated in the Battle of Nikolayevka.

During the dire retreat in the Russian steppe, he nearly fell victim to the freezing cold: dazed by frostbite, he would certainly have met the fate of thousands of other Italian servicemen, had not medical officer Rolando Prada (an offspring of the famous leather-working family) recognized him and put him on a passing military sled.

In those years the idea arose to create a charitable center that would take care of the victims of this war, which in the future developed as the origin of the Pro Juventute.

First, he directed his charitable work to the orphans of Alpini, housing them in Istituto Arosio (Institute Arosio) and subsequently devoted himself to the "mutilated" and to children invalids of war and civilians, establishing for them a vast network of colleges in many cities of Italy (Inverigo, Parma, Pessano con Bornago, Torino, Rome, Salerno, Milan, Firenze, Genova, ...); and, in the end, opened the doors of modern Centri di rieducazione ("Re-educations centers") for children affected by polio.

For this forsaken and handicapped children, to whom he had devoted all of his young life, Gnocchi dedicated one of his most significant writings: Pedagogia del dolore innocente (Pedagogy of Innocent Suffering).

"The dramatic experience of the retreat from Russia, lived as military ordinariate always on the front, matured in Gnocchi the idea and the focus of his charitable mission; assisting the victims of war, in search of redemption for their "innocent suffering".

In 1945, he was nominated as director of the Istituto Grandi Invalidi (Institute of Registered Invalids) of Arosio, thus accepting the first orphans and adults disabled by the war.

The same year, the Italian Prime Minister Alcide De Gasperi nominated Gnocchi as adviser to the Presidency of the Council for the mutilated by the war.

[16] On 17 January 2009, Pope Benedict XVI, with a papal decree recognized a miracle attributed to Gnocchi, a decisive step towards the beatification.