The opening of Foreword
Having found, after three weeks in our mobilization camp, that there was a great desire on the part of the officers and men of individual organizations to become acquainted with their co-workers, and realizing the necessity of personal contact for our mutual benefit to secure the co-ordination of each branch of the service into a unit of the highest possible efficiency, I have undertaken to compile this Roster. Any success attained is due to the hearty co-operation of Major-General William A. Mann, Colonel Douglass MacArthur, the Statistical Department and Officers of Division Headquarters.
The Rainbow Division was so christened by Secretary of War Baker when he assembled the official Forty-second because it represented organizations from twenty-six States of the Union, embracing a territory from coast to coast and from Maine to the Gulf of Mexico.