Compared to World War I, divisional organizations had rapidly adjusted to the demands of the Second World War. Initially three considerations greatly influenced the organization of the various divisions: the availability of men to field the units desired by the Army; the availability of shipping space to move them to the combat theaters; and the availability and quality of equipment. The last proved influential, continually forcing the Army to make structural changes to accommodate improved weapon systems or, in some cases, to eliminate those that proved less than successful in combat. In 1943 McNair attempted to reorganize divisional structures based on experiences acquired during the maneuvers of 1940 through 1942 and on the battlefield, where infantry, armored, and airborne divisions had to be augmented routinely, in particular to oppose tanks and airplanes. As the European war came to a close, the General Staff attempted to give infantry divisions the additional resources they habitually needed, but this effort came too late to benefit them during the conflict.
Before and during World War II the Army also sought to develop several new types of divisions and to achieve an acceptable balance between firepower and mobility. Planners tried not to sacrifice either capability to the other, seeking instead to serve both masters. This effort proved reasonably successful in the acid test of battle, especially by comparison with the performance of divisions during World War I. The accumulated experience of the twentieth century eased the task of making periodic organizational adjustments to satisfy changing requirements. Nevertheless, this evolutionary process would continue after World War II as the pace of technological developments and expanded global security roles of the United States Army forced it down roads that had never been traveled before.
