This book deals with the planning and the difficulties encountered incident to the mounting of the largest amphibious assault ever undertaken in military history. Much of the information it contains has not heretofore been a matter of public knowledge. For example, light is for the first time thrown upon the enemy's conflicting theories of defense against Allied air superiority and upon his paucity of first-class troops. This information is derived from the official records of the Wehrmacht and from signed statements of German participants. Many of the difficulties encountered in the planning, as well as in the execution stage of the operation, are here described to the public for the first time.