The purpose of this work by the Historical Section of the Army War College is to present the essential facts of the participation of the land forces of the United States in the World War. It deals with the command, composition, and operations of large units. This volume contains outline histories of the divisions which served in Europe during the war.
Original sources, the majority of which are official papers of the War Department, form the basis. The source references are on file in the Historical Section of the Army War College. The command lists were compiled for this SYSTEMation by The Adjutant General. The front lines of the divisions during battle are based primarily on a series of special studies by the American Battle Monuments Commission and an analysis by the Historical Section of the original material on file in the War Department.
The lists of the attached and detached units are limited to the larger combat echelons; units smaller than a regiment or independent battalion are not shown unless they were engaged in combat. The dates of attachment or detachment usually appear, but in a number of cases only the actual battle participation while present, or detached, is recorded.
Credit for participation in an operation is given a division from the time it entered corps reserve, provided the operation was in progress, or when it assumed command of a front without passing through corps reserve. Battle participation is shown as continuous when a division passed from a place in the line to corps reserve and then returned to the line; but any interruption in this sequence terminates the participation in that operation.
The dates of sector occupation, when American troops were affiliated with Allied troops for training, are fixed by the entry into line of the first American unit and the departure from the line of the last American unit. However, when an American division entered a sector to relieve another organization or assumed command of a sector in which it was affiliated with Allied troops, the dates of the sector occupation are governed by the passing of command.
The assignments show the armies and corps with which the divisions served. The arrival of the headquarters governs the date of entry into an area. Current orders furnish the dates of service in army reserve. A unit appears in corps reserve only pursuant to formal