This list of United States Army divisions is divided into three eras: 1911–1917, 1917–1941, and 1941–present. These eras represent the major evolutions of army division structure (there have been several minor changes during these times). The 1911–1917 era lists divisions raised during the Army's first attempts at modernizing the division, prior to the authorization of permanent divisions, and the 1917–1941 era lists the first permanent divisions, prior to advent of specialized (armored, airborne, etc.) divisions. The 1941–present era lists all of the divisions organized, raised, or authorized since then.
As much as possible, divisions are only listed in the eras in which they were first created. Some divisions, such as the 1st Cavalry Division, are listed in multiple eras, as their organizations were drastically changed from one era to the next. Many divisions overlap the years listed in the era categories, mainly due to the slow pace in which they were deactivated, inactivated, or otherwise disbanded.
Several divisions have existed under multiple designations, such as the 10th Mountain Division (10th Light Division (Alpine), 10th Infantry Division). Additionally, several divisions with the same numerical designations were completely separate and unrelated divisions (there have been two 5th Divisions, for instance).
History Divisions in the United States Army have existed since the American Revolution, but during the 18th and 19th centuries, these were temporary organizations.Wilson, J. B. (1998). Maneuver and Firepower: The Evolution of Divisions and Separates Brigades. United States: Center of Military History, U.S. Army. Pg. vii The concept of the permanent United States Army division was formulated and put to the test following the turn of the 20th century. In 1916, the permanent division would finally be authorized by Congress, resulting in a dramatic change in the Army's force structure. For the first time, the division was the base element of the United States Army and remained as such until the Global War on Terrorism, when the Army switched its emphasis to brigades and brigade combat teams.
Since the authorizations of permanent divisions, the United States Army has raised 128 separate divisions with unique lineages.
American Revolution George Washington organized the first divisions of the United States Army on 22 July 1775 in Boston, Massachusetts. Arriving to take command of the Siege of Boston, he split the forces there into three divisions, each composed of two brigades of six to seven regiments. These divisions were led by major generals but with no assigned staff. They were primarily administrative but eventually evolved into semi-permanent tactical organizations.Wilson (1998), p. 3McGrath, John J. The Brigade: A History, Its Organization and Employment in the US Army. (2004). Fort Leavenworth, KS : Combat Studies Institute, US Army Command and General Staff College. Pg 3
American Civil War During the Civil War, when the first large true field armies in United States history were formed, divisions were the Union Army's basic administrative and organizational unit.Wilson (1998), p. 12McGrath, p. 17-19 They were also the smallest "self-sufficient" units, each composed of two to six brigades. These were typically three brigades for infantry divisions and two brigades for cavalry divisions.Eicher, J., Eicher, D. (2002). Civil War High Commands. United States: Stanford University Press. p. 65 A division was typically commanded by a major general, but because Congress refused to promote officers past that grade (with the exception of promoting Ulysses S. Grant to lieutenant general in 1864) major generals were also put in charge of field armies and corps, allowing some divisions to be commanded by brigadier generals. Divisions were numbered sequentially within their corps, but were often referred to by the commander's name in official reports.
When the Army of the Potomac was first formed after the disastrous First Battle of Bull Run, the division was initially the largest unit. It consisted of three infantry brigades, a cavalry regiment, and four artillery batteries. However the cavalry and artillery were eventually spun off to their own units. When army corps were formally created in March 1862, half of the divisional artillery units were used to form an artillery reserve of three brigades for the army. After the Peninsula campaign the cavalry were removed from divisional control to form their own brigades under army control, until February 1863 when they were formed into a dedicated Cavalry Corps of three divisions, each with two brigades and assigned horse artillery. Following Chancellorsville all artillery batteries were removed from divisional control to form brigades under corps control.Wilson (1998), p. 13Wilson (1998), p. 14 The evolution of divisions within the Army of the Potomac served as a model by which the other field armies in the Union organized themselves.Wilson (1998), p. 15
In the beginning the division commander was allowed only an assistant adjutant general and three aides-de-camp as their staff. Administrative needs eventually led to the addition of a quartermaster, a commissary of subsistence, an ordnance officer, and a surgeon, all with the rank of major. However, there were no enlisted personnel specifically assigned to support duties, instead requiring either line soldiers be detailed to carry them out or civilian workers employed. The former removed the combat effectiveness of the units they were taken from, while the latter were more difficult to find and replace and tended to be less reliable and obedient.Shrader, C. R., Newell, C. R. (2011). Of Duty Well and Faithfully Done: A History of the Regular Army in the Civil War. United States: Nebraska. p. 71
Designations
Before 1941, only cavalry divisions were specifically designated; infantry divisions were simply designated by "Division". Following the advent of the armored division, infantry divisions became officially designated by "Infantry Division" (with the 25th Infantry Division being the first constituted by the adjutant general as such). All of the 1917–1941 (non-cavalry) divisions, with the exceptions of the 10th through 20th and 101st Divisions, would be redesignated as Infantry Divisions at some point in the 1941–present era.
Other than the aforementioned Armored, Cavalry, and Infantry, the only official Army division designations are Air Assault (one test division), Airborne, Light (three test divisions in World War II), Motorized (briefly authorized from 1942 to 1943), and Mountain. For lineage purposes, the 101st Airborne Division maintains its designation as an airborne division, though it is currently organized as an air assault division.
Divisions listed with an additional identifier in parentheses ("alpine" or "test", for example) existed only with that identifier. Divisions that have held multiple additional identifiers, such as the 1st Cavalry ("airmobile", "heavy") and the 9th Infantry ("light", "motorized"), are left unidentified, regardless of their current additional identifier.
An unspecified division today refers to a United States Army Reserve training division.
(*) denotes divisions that reorganized under a different division designation while still active Bold denotes current United States Army divisions
Divisions of the United States Army (1911–17) Maneuver Division (1911) – see History of the United States Army
Regular Army 1913–16 1st Division (Eastern Department) 2nd Division (Central Department) 3rd Division (Western Department) Cavalry Division: authorized as the Regular Army division for the Southern Department in 1913; never officially numerically designated. Punitive Expedition: (provisional division): 1916–17 National Guard 1914–17 5th Division 6th Division 7th Division 8th Division 9th Division 10th Division 11th Division 12th Division 13th Division 14th Division 15th Division 16th Division
National Defense Act of 1916 The National Defense Act of 1916 provided that the "Army of the United States" would consist of the Regular Army, the Volunteer Army, the Officers' Reserve Corps, the Enlisted Reserve Corps, the National Guard in the service of the United States, and such other land forces as were or might be authorized by Congress. The president was to determine both the number and type of National Guard units that each state would maintain. Both the Regular Army and the National Guard were to be organized, insofar as practicable, into permanent brigades and divisions. 5th Division: 1917* (26th Division) 6th Division: 1917* (27th Division) 7th Division: 1917* (28th Division) 8th Division: 1917* (29th Division) 9th Division: 1917* (30th Division) 10th Division: 1917* (31st Division) 11th Division: 1917* (32nd Division) 12th Division: 1917* (33rd Division) 13th Division: 1917* (34th Division) 14th Division: 1917* (35th Division) 15th Division: 1917* (36th Division) 16th Division: 1917* (37th Division) 17th Division: 1917* (38th Division) 18th Division: 1917* (39th Division) 19th Division: 1917* (40th Division) 20th Division: 1917* (41st Division)
Divisions of the United States Army (1917 to 1941)
Cavalry divisions In 1940, the National Guard voluntarily withdrew their allotment of the 21st through 24th Cavalry Divisions, partially in response to the Army's decision that the National Guard did not need four Cavalry Divisions and the Army's unwillingness to allot the National Guard armored divisions. The 61st through 66th Cavalry Divisions were inactivated in 1942. 1st Cavalry Division: 1921–present 2nd Cavalry Division: Unorganized. A 2nd Cavalry Division was constituted in 1921, but would remain unorganized until World War II. 3rd Cavalry Division: Unorganized. The 3rd Cavalry Division was placed on rolls in 1927 to complete an intended Cavalry Corps, but was never organized. 15th Cavalry Division: 1917–18 21st Cavalry Division: 1921–40 22nd Cavalry Division: 1921–40 23rd Cavalry Division: 1921–40 24th Cavalry Division: 1921–40 61st Cavalry Division: 1921–42 62nd Cavalry Division: 1921–42 63rd Cavalry Division: 1921–42 64th Cavalry Division: 1921–42 65th Cavalry Division: 1921–42 66th Cavalry Division: 1921–42
Infantry divisions
Various elements of the 4th through 9th Divisions remained on active duty until those divisions' full activation prior to World War II.
The 76th through 91st and 94th through 104th Divisions existed primarily as officer billets with enlisted cadre; they were not completely reactivated until America's entry into World War II.
The infantry brigades, field artillery brigades, and several other of the subordinate units of the Panama Canal, Hawaiian, and Philippine Divisions were numbered accordingly with what should have been the 10th, 11th, and 12th Divisions.
1st Division (later 1st Infantry Division): 1917–present 2nd Division (later 2nd Infantry Division): 1917–present 3rd Division (later 3rd Infantry Division): 1917–present 4th Division: 1917–1921; 1940–1946; 1947–present 5th Division: 1917–1921; 1939–1946; 1947–1992 6th Division: 1917–1921; 1939–1949; 1986–1994 7th Division: 1917–1921; 1940–1971; 1974–1994; 1999–2006; 2012–present 8th Division: 1918–1919; 1940–1945; 1950–1992 9th Division: 1918–1919; 1940–1947; 1947–1962; 1966–1969; 1972–1991 10th Division – Organized in 1918 as a Regular Army and National Army division for World War I, the 10th Division did not go overseas and demobilized in February 1919 at Camp Funston, Kansas. 11th Division: 1918–1919 12th Division: 1918–1919 at Fort Devens, Mass. 13th Division: 1918–1919 at Fort Lewis 14th Division: 1918–1919 – Organized in 1918 as a Regular Army and National Army division for World War I, the 14th Division did not go overseas and demobilized in February 1919 at Camp Custer, Michigan.