During the Second World War, a little-known story is that of the Mafia's contribution to Allied military operations. The Germans had conducted several sabotage operations in American military port complexes and possessed numerous spies. The American intelligence services needed men who were perfectly familiar with the port areas and the people working there to counter the German spies. So it was that Boss 'Lucky' Luciano and the Italian-American Mafia started to cooperate with the military institutions to counter espionage and sabotage activities. Luciano, who was in prison, managed to obtain better living conditions in his cell in exchange for his support. This marked the beginning of a collaboration between the Mafia and the Allies that would last for much of the conflict.

During the twenty-year Fascist period, Mussolini's regime had almost succeeded in the almost impossible task of destroying the Sicilian Mafia, in particular thanks to the work of Prefect Cesare Mori. This led the Italian Mafia to develop a strong hostility towards Mussolini's regime, which ruined their business and fought them with all its might. When the Allies began planning Operation Husky, the invasion of Sicily, they found an unexpected and important local partner in the Mafia. The Mafia bosses knew the territory and the population and, through the mediation of the Italian-American Mafia, they came into contact with the local Sicilian Mafia, making local resistance to the arrival of American and British troops less bitter.

Unfortunately, this proved to be an effective as well as controversial weapon and the American troops, who had exploited the Mafia as effective local stabilisation tools in the aftermath of the landing in Sicily, inevitably contributed to reinforcing and restoring the old strength of a criminal organisation that had been almost completely destroyed by the Mussolini regime. After the war, Mafia bosses returned to control local communities and carry out their criminal activities.