Douglas MacArthur participant of World War I
World War I
Rainbow Division
MacArthur returned to the War Department, where he was promoted to major on 11 December 1915. In June 1916, he was assigned as head of the Bureau of Information at the office of the Secretary of War, Newton D. Baker. MacArthur has since been regarded as the Army's first press officer. Following the declaration of war on Germany on 6 April 1917 and the subsequent American entry into World War I, Baker and MacArthur secured an agreement from President Wilson for the use of the National Guard on the Western Front. MacArthur suggested sending first a division organized from units of different states, so as to avoid the appearance of favoritism toward any particular state. Baker approved the creation of this formation, which became the 42nd ("Rainbow") Division, and appointed Major General William A. Mann, the head of the National Guard Bureau, as its commander; MacArthur was its chief of staff, with the rank of colonel. At MacArthur's request, this commission was in the infantry rather than the engineers.The 42nd Division was assembled in August and September 1917 at Camp Mills, New York, where its training emphasized open-field combat rather than trench warfare. It sailed in a convoy from Hoboken, New Jersey, for France on 18 October 1917. On 19 December, Mann was replaced as division commander by Major General Charles T. Menoher.