42nd Division (United States)

42nd Division (United States)
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Unit name	42nd Division (United States)
Caption	Shoulder sleeve insignia of the division
Dates	1917–1919; 1921–1945; 1946–present
Country	United States
Branch	Army
Type	Infantry (World War I); Infantry/Armored/Mechanized (later)
Role	Combat operations, National Guard readiness
Size	Division
Nickname	Rainbow Division
Battles	World War I: Second Battle of the Marne, Oise-Aisne; World War II: Rhineland, Central Europe
Notable commanders	Douglas MacArthur, Charles S. Farnsworth, William A. Mann, Harry J. Collins
Identification symbol label	Shoulder sleeve insignia

42nd Division (United States) was a major United States Army formation raised in 1917 that earned renown in World War I as the "Rainbow Division" and served through World War II into the modern United States Army National Guard. The division drew personnel and units from multiple state National Guards, fought under combined Allied command, and underwent repeated reorganizations during the twentieth century as doctrines and force structures changed. Its history intersects with leaders, campaigns, and institutions across American and Allied military history.

Formation and Organization

The division originated in 1917 when Secretary of War Newton D. Baker and Chief of Staff Erasmus D. Keyes (note: Keyes was an earlier figure) approved a multi-state formation concept promoted by Major General William A. Mann and brigadier leaders from the New York National Guard, New Jersey National Guard, Connecticut National Guard, Massachusetts National Guard, Pennsylvania National Guard, Rhode Island National Guard, Vermont National Guard, and New Hampshire National Guard. Commanded initially by Major General William A. Mann and later by Major General Charles S. Farnsworth, the division was organized into numbered infantry brigades and artillery brigades drawn from constituent state units, with staff officers coordinating logistics with the Quartermaster Corps, Adjutant General's Department, and American Expeditionary Forces supply services. The nickname "Rainbow" was popularized by staff officers invoking a symbolic arc from coast to coast and was adopted across unit insignia, press reports in The New York Times, The Washington Post, and veterans' organizations such as the American Legion.

World War I Service

After mobilization at Camp Mills and training at Camp Wadsworth, the division sailed for France and entered the line under the command of General John J. Pershing's American Expeditionary Forces (AEF), operating in concert with French and British formations during 1918. The division fought in major operations including the Second Battle of the Marne, the Battle of Saint-Mihiel in coordination with Army of Occupation, and the offensives in the Oise-Aisne sector, earning citations from commanders such as Marshal Ferdinand Foch and coordination with units of the British Expeditionary Force and French Fourth Army. Notable figures associated with the division's wartime service included then-Colonel Douglas MacArthur, who served as a staff officer and publicist for its actions, and Lieutenant Colonel Eugene Reybold (later Chief of Engineers). The Rainbow Division received numerous decorations including Distinguished Service Cross awards and unit citations for actions at Murfreesboro and in operations near Château-Thierry, interacting with allied institutions like the Legion of Honour and receiving coverage in Stars and Stripes.

Interwar Period and Reconstitution

Demobilized in 1919 following the Armistice of 11 November 1918 and reconstituted in 1921 under the National Defense Act of 1920, the division was reorganized within the New York National Guard and other state formations. During the interwar years, division training involved summer camps at Camp Smith, association with the Citizens' Military Training Camp program, and participation in relief and ceremonial duties during events in New York City, Albany, New York, and national observances involving the War Department. Leaders like Major General George B. Duncan and staff members engaged with the United States Army War College curricula and Reserve Officers' Training Corps links at institutions such as Columbia University and Rutgers University while veterans' groups including the Veterans of Foreign Wars maintained divisional traditions.

World War II and Postwar Activities

Federalized again in 1940 amid mobilization measures overseen by Franklin D. Roosevelt and Harry S. Truman as President in the late war period, the division trained at installations including Camp Gruber and Fort McClellan before deploying elements to the European Theater. In World War II the division, reorganized under triangular division doctrine influenced by the Army Ground Forces and General George C. Marshall, fought in the Rhineland Campaign and the Central Europe Campaign, operating alongside formations such as the U.S. Seventh Army, U.S. Ninth Army, and Allied partners including the British Second Army. Postwar demobilization in Europe and return to National Guard status led to reassignment of regiments and conversion of units to armor and artillery under the National Guard Bureau and the Department of the Army.

Cold War Role and National Guard Service

During the Cold War, the division's descendants served as a strategic reserve within the United States National Guard system, subject to the Selective Service Act's manpower infrastructure and integrated training with NATO exercises and continental defense initiatives. Reorganizations under the Pentomic and later Reorganization Objective Army Divisions (ROAD) concepts produced mechanized, armored, and aviation elements aligned with Army National Guard modernization programs, while units were activated for crises including the Berlin Crisis of 1961 and mobilizations during the Vietnam War era for support missions. The division's components participated in peacekeeping, homeland support during natural disasters affecting New Jersey, New York, and Connecticut, and in later deployments supporting operations related to Operation Desert Storm and global contingency commitments coordinated by U.S. Central Command and U.S. Northern Command.

Unit Structure, Insignia, and Traditions

The division's organization evolved from square-division brigades to triangular infantry regiments and later to brigade combat team constructs, with subordinate units including infantry regiments, field artillery battalions, engineer battalions, signal companies, and support units tied to institutions like the Ordnance Corps and Medical Department (United States Army). The shoulder sleeve insignia—a multicolored arc design—became emblematic and is preserved in museum collections at the National Infantry Museum, New York State Military Museum, and private collections. Traditions such as the Rainbow nickname, unit marches performed at ceremonies involving the United States Army Band (Pershing's Own), and annual reunions sponsored by the Rainbow Division Veterans Association and veteran networks maintain continuity with ceremonies at battlefield memorials like those in Château-Thierry and at the World War I Centennial Commission events. The division's lineage continues in current National Guard brigades and units, linking historical regiments with modern formations under the oversight of the National Guard Bureau.

Category:Infantry divisions of the United States Army Category:United States Army divisions of World War I Category:United States Army divisions of World War II