World War II saw the systematic use of strategic, or area, bombing. The aim of this was to sabotage production and damage infrastructure, but also to terrorise and undermine the life and morale of enemy populations.

Italy was hit hard by British raids, which were joined in 1943 by American raids from North Africa. The most affected cities included those in the industrial triangle, where the country's industrial production and military reserves were concentrated. Milan was bombed as early as June 1940 and underwent minor damage. However, the most serious consequences were from the raids of October 1942, February and August 1943, and of course October 1944. The last air raid took place on 13 April 1945. In total, they suffered more than 60 bombardments.

To defend themselves, the citizens had only a few unsafe shelters available. The first air-raid shelters were basically the cellars of buildings, but the only shelters that offered decent guarantees of safety were those built of reinforced concrete. Despite these measures, there were more than 60,000 civilian victims of bombings in Italy, and more than 2,000 in Milan alone. Over 300,000 people were displaced.

The case of Gorla is undoubtedly the most well known. On 20 October, American bombers of the 451st Bomber Group took off from Foggia to hit the Breda workshops under the command of Colonel James B Knapp. Owing to a miscommunication, they found themselves with bombs primed far from the target, but instead of dropping them on the return path or at sea they dropped them on the city. More than 300 bombs with over 80 tonnes of explosives were unloaded.

In particular, an explosive device penetrated the stairwell of the Francesco Crispi primary school while classes were in progress, causing the death of 184 children, 14 teachers, 5 employees and the school headmaster. In total there were 614 victims in Milan that day.

As early as 1947, an ossuary (burial place) was erected, then thanks to donations from Falck and Rinascente a monument was created. This monument, the work of Renato Brioschi, was inaugurated in 1952. Piazza Redipuglia was renamed Piazza Piccoli Martiri di Gorla, and the new primary school in the district was also dedicated to the Little Martyrs of Gorla.