Editing Douglas MacArthur (section)

===Rainbow Division===
[[File:Douglas MacArthur, Army photo portrait seated, France 1918.JPEG|thumb|upright|left|Brigadier General MacArthur holding a [[riding crop]] at a French château, September 1918|alt=A man sits in an ornate chair. He is wearing a peaked cap, greatcoat and riding boots and holding a riding crop.]]

MacArthur returned to the War Department, where he was promoted to [[Major (United States)|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.{{sfn|Zabecki|Mastriano|2020|p=90}}

Following the [[United States declaration of war on Germany (1917)|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 of the United States|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 Infantry Division (United States)|42nd ("Rainbow") Division]] and appointed Major General [[William Abram Mann]], the head of the [[National Guard Bureau]], as its commander; MacArthur was its chief of staff, and with his new role came the rank of [[Colonel (United States)|colonel]], skipping the rank of lieutenant colonel.{{sfn|Zabecki|Mastriano|2020|p=91}} At MacArthur's request, this commission was in the infantry rather than the engineers.{{sfn|James|1970|pp=130–135}}{{sfn|Manchester|1978|p=79}}

{{Blockquote|From its formation at [[Camp Mills]], [[Long Island]] in August 1917, MacArthur was the division's key sparkplug, prime motivator, and individual most responsible for its creation. Competent, efficient, innovative, highly intelligent, and tirelessly energetic, as division chief of staff MacArthur appeared everywhere, at all hours – badgering, cajoling, inspiring, intervening, and attending to every detail, large and small.{{sfn|Zabecki|Mastriano|2020|pp=91–92}}}}

The 42nd Division's initial training emphasized open-field combat rather than [[trench warfare]]. It sailed in a convoy from [[Hoboken, New Jersey]], for the [[Western Front (World War I)|Western Front]] on 18 October 1917. On 19 December the 42nd's commander, the 63-year-old Mann, was replaced by 55-year-old Major General [[Charles T. Menoher]], after Mann–who was "ill, old, and bedridden"–{{sfn|Manchester|1978|p=84}} failed a physical examination.{{sfn|James|1970|p=148}}{{sfn|Zabecki|Mastriano|2020|p=95}} The new division commander and his chief of staff "became great friends", in MacArthur's words, who further described Menoher as "an able officer, an efficient administrator, of genial disposition and unimpeachable character".{{sfn|MacArthur|1964|p=54}}