I'm not a historian, however I studied history in college and wrote a paper on Lucky Luciano and his assistance during the Second World War. I'll include some of the books I used for it on the topic at the end. It all started with the sinking of the S.S. Normandie. The French ship was docked in New York Harbor in 1942 when it caught fire and capsized. The papers and the government believed it was sabotaged by German spies. (How ever many today believe it to have been sparked by welders working on the renovation of the ship for troop and cargo transport) However this caused the US to want to keep the harbors safe, not being ignorant, they knew the Mafia controlled many aspects of the docks' workers and business. Salvatore 'Lucky' Luciano was in prison at the time, so Naval Intelligence began correspondence and meetings with him. No such instance like the Normandie ever happened again, whether that was due to the mafia's influence is debatable. His biggest asset to the war effort was with the invasion of Sicily. After the Allies defeated Germany in north Africa they wanted to make contact in mainland Europe with pressure from the Soviets to create a Western front. Also they had the opportunity to cut off half the Mediterranean by invading Sicily and pushing up the Italian Peninsula. Intelligence again contacted Luciano and he cooperated by giving names and locations of people in Sicily that would help. Many Sicilians compiled to Luciano's requests (he didn't have direct contact obviously sitting in a cell in upstate NY, but associates helped him) helped the Allies by pointing out snipers, boobie traps by retreating soldiers, and by creating a communication network around the island of troop movements. Some even took to arms for the allies all under the orders of Cosa Nostra and connections to Luciano. Many Allied troops' lives were saved due to the help from the Sicilians allied with Luciano and his organization. The invasion was a success and for his help Luciano was eventually released from American Prison and deported to Italy were he lived out his remaining years, arguably, an American hero. The books I used, and still own, alongside the primary sources I no longer have access to are: Mafia Allies by Tim Newark (My favorite of them) The Mafia and the Allies by Ezio Costanzo The Luciano Project by Rodeny Campbell

If i remember right I believe all three are available on google books if you care to read. If any of you have Jstore theres many articles from the New York times and some North Jersey papers about the subject. Hope this helps.