History of the 151st field artillery, Rainbow Division, by Louis L. Collins, lieutenant governor of Minnesota. Edited by Wayne E. Stevens, PH. D. Pub. by the Minnesota War records commission.

16 HISTORY OF THE 151ST FIELD ARTILLERY

possible, both because they were needed in the battle line and because
their presence would stiffen the morale of the allies. Another consideration of equal importance was the effect which the sending of a composite division representing all sections of the country would have upon
the nation at large. The dispatch of regular army troops was taken
more or less as a matter of course, but nothing would bring the war
home to the whole country so effectively as the transportation of
these local units to France at the earliest possible moment.
The enthusiasm with which the announcement of the organization of the Rainbow Division was everywhere received fully
justified all expectations. Units from twenty-six states and the District of Columbia were assigned to it and nearly all sections of the
country were represented, from California in the west to Maryland and New York in the east and from Minnesota in the north
to Louisiana and Texas in the south. New England was the
only section of the country not represented.10 The division was to
be assembled at Camp Mills, on Long Island, and orders were
given for its concentration at the earliest possible date."
10 New England had its own division, the 26th.
"1It is perhaps desirable to explain briefly at this point the composition of
the combat division of the United States army during the World War. The
combat division is a unit which is self-supporting in the military sense, being
capable of operating in the field as an independent unit and having its own
supply system. The division commander and his staff, together with the attached troops, are known collectively as "division headquarters." The "headquarters troop," acting under the orders of division headquarters, provides for
the security and general welfare of the commanding general and his staff. Two
infantry brigades are included, each commanded by a brigadier general and
each comprised of a machine gun battalion and two infantry regiments. A
third machine gun battalion is unattached to either of the infantry brigades.
The one field artillery brigade, also commanded by a brigadier general, is
comprised of a trench mortar battery and three regiments of artillery, two
light and one heavy; its principal function is to support the infantry in its
operations. The necessary field construction, such as bridge-building and roadrepairing, is in charge of a regiment of engineers, which is supplied by an
engineer train with the material required for this purpose. A field signal
battalion constructs telephone lines and provides other means of communication
in the field. Finally, various trains attend to matters of supply and the evacuation and care of the wounded. An organization known as " train headquarters
and military police" is responsible for the administrative work connected with
the management of the trains and also polices the area occupied by the division,
enforces military regulations, and rounds up stragglers. The ammunition train
brings up ammunition from the rear to the point where it can be delivered to
the various regiments. Similarly, the supply train brings up food, clothing, and
necessary equipment. The sanitary train, including four ambulance, and four
field hospital companies, is charged with the care of the sick and wounded in
the field until they can be evacuated to the rear.