On April 6, 1917, the United States Congress declared war on the German Empire and entered the Great War.  In the rush to mobilize troops, individual states competed with each other for the honor to be the first to send their National Guard units into combat.  Secretary of War Newton D. Baker authorized the organization of a Division made up of National Guard units from 26 different states and the District of Columbia.

Douglas MacArthur, who at the time was a Major working at the office of the Secretary of War, is credited with saying “The 42nd Division stretches like a Rainbow from one end of America to the other.”  MacArthur was instrumental in the formation of the Division and was appointed its Chief of Staff and promoted to Colonel.

The 42nd (Rainbow) Division was activated in August 1917 and arrived in France that November.  During its time in France the Rainbow Division participated in six major campaigns and suffered over 50% casualties.

Following the end of WWI, the officers of the Rainbow Division formed the Rainbow Division Veterans Association, which eventually became the Rainbow Division Veterans Foundation, a 501 (c)(3) non-profit corporation.