The entrance of the United States into World War II created transportation problems of unprecedented scope and complexity. Requirements for the deployment of military forces and materiel to oversea commands and their intratheater movement dwarfed those of World War I, in which men and supplies were moved over a relatively short sea line of communications to well-established, protected ports for action on a single major front. In World War II much larger forces were employed overseas on far-flung active and inactive fronts. Their deployment and support, as well as the provision of considerable assistance to our Allies, made it necessary to spread shipping over sea lanes encircling the globe. The reception and distribution of cargoes and personnel in the theaters were rendered more difficult by the lack of port, storage, and other base facilities in many areas of the Pacific, the North Atlantic, and Alaska; by extensive destruction of ports and railroads in France and Italy; and by unsatisfactory lines of communication in such backward areas as North Africa, Iran, and India. Furthermore, amphibious operations on a scale hitherto undreamed of had to be undertaken in both the transatlantic and the transpacific theaters in order to come to grips with the Axis powers and to advance on their homelands. The movement of assault forces and their equipment to and across beaches alone constituted transportation tasks of great magnitude.