GARDEN CITY, N.Y.-- The 42nd Infantry Division, a part of the New York National Guard since 1947, was born a 100 years ago on August 5, 1917 as a way to get 27,000 troops to France quickly during World War I.The United States had entered what was then known as the Great War in early April but no American Soldiers had yet been dispatched to France.The small regular Army, which was supposed to provide four division's worth of troops was dispersed across the country in regiments of about 1,000 men. Other Soldiers were in Hawaii, the Philippines, Cuba and Puerto Rico. It would take time to bring those troops together into divisions of 27,000 men.President Woodrow Wilson mobilized the National Guard, with 122,000 members on July 12, 1017, but getting those troops into fighting shape would also take time. The New York and Pennsylvania National Guard's had division-sized units, and New York's Soldiers had just served on the Mexican Border in 1916, so these units could probably be readied to deploy relatively quickly.But the War Department was concerned that if one of these state divisions went to France first it would look like favoritism and anger other sections of the country.So Major Douglas MacArthur-later to be five-star general Douglas MacArthur during World War II and the Korean War-- had a good idea. Take National Guard units from across the country and combine them into one division. That division could then be deployed to France without slighting any particular state or region.In describing the division, first to his superiors and then later to newspaper reporters - MacArthur was then also acting as the War Department's press person-MacArthur said the division would stretch across the United States "like a rainbow."So the division, still without a number, quickly became known as "The Rainbow Division" and McArthur would soon be promoted to colonel as made the division's first chief of staff.As the Army began to stand up divisions to fight in France, it was decided to reserve designations 1 through 25 for the divisions created by using the Regular Army as a base.Numbers 26 through 41 would be reserved for division's formed by individual state National Guards and for divisions formed from the National Guards of a particular region. The division formed from New England National Guard units for example, was given number 26. The New York Division would become the 27th Infantry Division.The Rainbow Division, since it was a composite of units from states across the country was given number 42.Eventually, 26 states and the District of Columbia would be tapped for troops to comprise the Rainbow Division.The units were told to report to Camp Mills just outside Garden City, Long Island on August 20.The New York National Guard contributed its famous 69th Infantry Regiment, known as the "Fighting 69th" from its service in the Civil War as an Irish-American unit. Soldiers came from other New York National Guard regiments to bring the 69th up to its wartime strength.All of the state units were given new designations to reflect the fact that they were now part of the United States Army and not their state National Guard. The 69th Infantry was renamed the 165th U.S. Infantry.The regiment's headquarters detachment became the headquarters of the 83rd Infantry Brigade-one of two brigades in the division. The Ohio National Guard's 4th Infantry Regiment, which became the 166th U.S. Infantry, joined the New Yorkers at Camp Mills as part of the brigade.Other major units came from Alabama, Iowa, and Indiana. Since the Civil War's 50th anniversary had been marked only four years earlier, much was made of having Soldiers from the north and south serving side-by-side. The Alabama unit, for example, had fought against the New York regiment at Gettysburg.For all the talk of covering the United States like a Rainbow, the division was not all inclusive.When the commander of the 15th New York Infantry, an African-American regiment in a segregated Army, asked to join the 69th Infantry and other 42nd Infantry Division units in a farewell parade through New York City, he was told no. New York might have been the hometown of the unit which would gain fame as the Harlem Hell Fighters, but Col. William Hayward was reportedly told that black was not a color of the rainbow.The Rainbow Division was the fourth unit to land in France and was one of the most famous of the war. Newspapers followed the exploits of the division and poet Joyce Kilmer- -the author of the poem "Trees"-who was killed in action wrote poems about the troops.There were songs written about the division with titles like: "The Rainbow Lads," "A Tribute to the Rainbow Division," "The Rainbow Division" , "When the Rainbow Division Arrives, " and "There's Green in Every Rainbow", about the 69th Regiment.After the war Rainbow Division reunions were big news, books about the Rainbow Division sold well, and in 1940 a Hollywood movie "The Fighting 69th" starring Jimmy Cagney and Pat O'Brien as Father Duffy, the chaplain of the 69th Infantry, told the division's story.In 1943 the division was reactivated to fight in World War II and liberated the Dachau concentration camp in the spring of 1945.Since 1947, the division has been part of the New York National Guard, serving as part of the Army's strategic reserve during the Cold War, responding to state emergencies, and deploying Soldiers to Iraq in 2004/2005.During the World War I centennial observance, the New York State Division of Military and Naval Affairs, based on information provided by the New York State Military Museum in Saratoga Springs, N.Y., will issue press releases noting key dates of WWI history which impacted New Yorkers. More than 400,000 New Yorkers served in the military during World War I, more than any other state.