In stark contrast to the rather modest performance of its large surface fleet in the Second World War, the Italian Navy's smallest units achieved its most spectacular successes. It made a speciality of unconventional methods of attack - explosive motor boats, human torpedoes and miniature submarines - that were employed with ingenuity and daring to surprise, discomfort and baffle the enemy. In December 1941 the whole balance of the naval war in the Mediterranean was altered by six frogmen riding three of the SLC craft they called maiale ('pigs') who penetrated Alexandria harbour to cripple the battleships Valiant and Queen Elizabeth, surely one of the most impressive ratios of results to resources in naval history. This book is the first complete history of these craft, both the details of the technology and the history of their deployment. Beginning in the Great War with the extraordinary 'jumping' boats designed to scale harbour boom defences, the story takes in the inter-war development of both lightweight surface craft and underwater systems from small submarines to 'Gamma' assault divers. By way of comparison, equivalent developments in other navies are analysed, including the British 'chariots' which were little more than copies of the Italian SLCs. Every operation by these craft is described, cataloguing the forces involved and the results, from high-profile successes like the sinking of the cruiser York by explosive motorboat to lesser-known incidents - the use of such craft by the Israelis as late as 1948 for example. Many were carried out by the famous Decima MAS, a unit as legendary in Italy as the SAS in Britain, and this book provides a comprehensive chronicle of their activities. Originally commissioned by CABI Cattaneo that designed and built most of these craft, Italian Assault Craft benefited from unrestricted access to the company's archives, technical drawings, and photo collection so it is replete with rarely seen illustrations. Very much secret weapons in their day, they are here revealed in full detail for the first time.