As the United States geared up for entry into the Great War in 1917, a unit unlike any other in the U.S. Army was formed amid considerable political and military debate. Comprised of National Guard troops from 26 states and the District of Columbia, the Chief of Staff of the newly-created 42nd Division, Colonel Douglas MacArthur, remarked that the 42nd was truly a “national” unit, with its component units stretching across the country from coast to coast “like a rainbow.” The name stuck and the 42nd became known as the “Rainbow Division.” Could men from all across the United States be melded into an effective fighting force, and perhaps more importantly could politicians from so many different and diverse states be convinced that such a military and social experiment could work? The Rainbow Division amassed one of the finest fighting records of any division – regular, volunteer or National Guard – in the American Expeditionary Force. From its activation in August 1917 through the Armistice in November 1918 the 42nd was in combat longer than any other American division and suffered more than 50% casualties. 

Within the ranks and officer corps of the Rainbow Division were men from all walks of life: farmers from the Midwest, shopkeepers from New York City, students from Chicago, nearly all of whom had joined the National Guard not with the idea of going to war in Europe but rather seeking financial income. The Division also included a number of men who would play a significant role in American history: MacArthur; poet Joyce Kilmer; William “Wild Bill” Donovan, head of the Office of Strategic Services – forerunner of the CIA – during World War II; Father Francis Duffy, prominent Catholic leader in New York City; Charles Summerall, future Army Chief of Staff; Charles Menoher, first Chief of Army Air Service; Cooper Winn, instrumental in the preservation of Robert E. Lee’s birthplace Stratford Hall. 

Under the Rainbow begins the centennial anniversary of the Great War, which began in Europe in 1914. This exhibit tells the story of the officers and men of the Rainbow Division from its inception at Camp Mills, New York in the summer of 1917, across the battlefields of France, and into occupation service in Germany until the dissolution of the division in the spring of 1919. Many of the items exhibited have never before been on display at the MacArthur Memorial, and includes uniforms, equipment and personal items of the men of the Rainbow as well as other Allied countries and Central Powers. Among the highlights are uniform and equipment of Lt. Col. Cooper Winn, commander of the 151st Machine Gun Battalion; dog tag of the poet Joyce Kilmer, killed at the Battle of the Marne in July 1918; set of German trench armor; and an extensive collection of Rainbow Division Veterans Association memorabilia. The exhibit opened on October 12, 2012 and closed on December 5, 2014.