Dozens of books have been written about German submarines that hunted Allied ships in three oceans, individually and in so-called “wolf packs.” Few people know that the submarines of the Regia Marina (Italian fleet) also actively participated in the battle for the sea. Meanwhile, Mussolini’s submarine fleet at the beginning of World War II was larger than that of any other country, even than that of Nazi Germany. And the Italian captains could compete with their German colleagues in courage, adventurism and propensity for suicidal attacks. And unlike the surface fleet of the Italian Navy, which fought ingloriously, the Duce’s submariners acted quite professionally and effectively. The submarines reached the shores of America and South Africa, and they accounted for dozens of confirmed sunk ships and ships in the Atlantic and Indian Ocean. In this book, the author for the first time collected detailed information about the actions of Mussolini’s submarines, their tactics, the results of torpedo attacks, as well as about the most famous submarines and their commanders.