Department is an organizational term used by the

U.S. Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

, mostly prior to

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, to describe named geographical districts created for control and administration of installations and units. In 1920, most of the named departments were redesignated as numbered

Corps Area A Corps area was a geographically-based organizational structure (military district) of the United States Army used to accomplish administrative, training and tactical tasks from 1920 to 1942. Each corps area included divisions of the Regular Army ...

s. However, the Hawaiian,

Panama Canal The Panama Canal ( es, Canal de Panamá, link=no) is an artificial waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean and divides North and South America. The canal cuts across the Isthmus of Panama and is a conduit ...

, and

Philippine Department The Philippine Department (Filipino: ''Kagawaran ng Pilipinas/Hukbong Kagawaran ng Pilipinas'') was a regular United States Army organization whose mission was to defend the Philippine Islands and train the Philippine Army. On 9 April 1942, durin ...

s retained their old names. In 1939, the

Puerto Rican Department Puerto, a Spanish word meaning ''seaport'', may refer to: Places *El Puerto de Santa María, Andalusia, Spain *Puerto, a seaport town in Cagayan de Oro City, Philippines *Puerto Colombia, Colombia *Puerto Cumarebo, Venezuela *Puerto Galera, Orient ...

was created and in May 1941 the Panama Canal and Puerto Rican Departments were combined as the

Caribbean Defense Command The United States Southern Command (USSOUTHCOM), located in Doral, Florida in Greater Miami, is one of the eleven unified combatant commands in the United States Department of Defense. It is responsible for providing contingency planning, op ...

, although each was still referred to as a department.

1800s

War of 1812

The United States Army was divided into nine military districts by the

War Department War Department may refer to: * War Department (United Kingdom) * United States Department of War (1789–1947) See also * War Office, a former department of the British Government * Ministry of defence * Ministry of War * Ministry of Defence * Dep ...

General Order, of 19 March 1813. They were increased to ten on 2 July 1814 but reduced to nine by consolidation of the 4th and 10th Military Districts in January 1815. Military districts were abolished, 17 May 1815.

1815–21

At the end of the War of 1812, Military districts were superseded by ten Military Departments, divided equally between Divisions of the North and South, 17 May 1815. *

Division of the North The Division of the North ( es, División del Norte) was a Spanish infantry division that existed in 1808. Spain was, at that time, an ally of France and the division, composed of 15,000 men under the command of the Marquis de la Romana, Pedro ...

, 17 May 1815 – May 1821 ** 1st Military Department, 1815–17 ** 2nd Military Department, 1815–18 ** 3rd Military Department, 1815–17 ** Consolidated 1st and 3rd Military Departments, 1817–19 ** Consolidated 1st and 3rd Military Departments, 1818–21 ** 4th Military Department, 1815–19 ** Consolidated 1st, 3rd, and 4th Military Departments, 1819–21 ** 5th Military Department, 1815–21. * Division of the South, 17 May 1815 – May 1821 ** 6th Military Department, 1815–1821 **

7th Military Department 7 (seven) is the natural number following 6 and preceding 8. It is the only prime number preceding a cube. As an early prime number in the series of positive integers, the number seven has greatly symbolic associations in religion, mythology, s ...

, 1815–1821 ** 8th Military Department, 1815–19, 1820–21 ** 9th Military Department, June 1819 – June 1821 ** 10th Military Department, 1815–1821

1821–1837

Reorganization of the Army into Eastern and Western Departments, May 1821. *

Eastern Department Eastern may refer to: Transportation *China Eastern Airlines, a current Chinese airline based in Shanghai *Eastern Air, former name of Zambia Skyways *Eastern Air Lines, a defunct American airline that operated from 1926 to 1991 *Eastern Air Li ...

, 1821–37 *

Western Department The Department of the West, later known as the Western Department, was a major command (Department) of the United States Army during the 19th century. It oversaw the military affairs in the country west of the Mississippi River to the borders of Ca ...

, 1821–37 ** Right Wing, Western Department, 1832–37 ** Army of the Frontier, 1832 ** 1st Army Corps, North West Army, 1832 ** Army of the Southwestern Frontier, 1834–37

1837–1844

From 1837 to 1842, some of the Departments were subordinated to the Eastern and Western Divisions. * Eastern Division, 1837–42 ** 7th Military Department, 1837–41 * Western Division, 1837–42 ** 1st Military Department, 1837–42 ** 2nd Military Department, 1837–42 ** 7th Military Department, 1841–42 * 1st Military Department, 1843 * 2nd Military Department, 1843–51 * 3rd Military Department, 1842–48 * 4th Military Department, 1842–53 * 5th Military Department, 1842–52 * 8th Military Department, 1842–46 * 9th Military Department, 1842–45 (Florida)

1844–1848

The Eastern and Western Divisions were not restored until 1853. * Eastern Division, 1844–48 ** 5th Military Department, 1844–48 ** 8th Military Department, 1844–46 * Western Division, 1844–48 ** 2nd Military Department, 1844–48 ** 3rd Military Departments, 1844–48 * 4th Military Department, 1842–53 * 9th Military Department, 1845 * 10th Military Department, 1846–1853 (California and Oregon to 1848)

1848–1853

All departments were subordinated under one of three Divisions. * Eastern Division, 1848–53 ** 1st Military Department, 1848–53; consolidated 1st and 3d Military Departments, 1849–50 ** 2nd Military Department, 1848–51; consolidated 1st and 2d Military Departments, 1848–49 ** 3rd Military Departments, 1848, 1850–53 ** 4th Military Departments, 1848–53; consolidated 3d and 4th Military Departments, 1848 * Western Division, 1848–53 ** consolidated 5th and 6th Military Departments, 1848 ** 5th Military Department, 1848–52 ** 6th Military Department, 1848–53 ** 7th Military Department, 1848–53 ** 8th Military Department, 1848–49, 1851–53 ** 9th Military Department, 1849–53 (New Mexico) * Pacific Division, 1848–53,(California and Oregon) ** 10th Military Department, 1846–1853 (California and Oregon to 1848) **

11th Military Department 11 (eleven) is the natural number following 10 and preceding 12. It is the first repdigit. In English, it is the smallest positive integer whose name has three syllables. Name "Eleven" derives from the Old English ', which is first attested i ...

, 1848–1853 (Oregon)

1853–1861

After 31 October 1853 the division echelon was eliminated and the six western departments consolidated into four (Departments of Texas, New Mexico, the West, and the Pacific), whose department commanders employed their troops as they saw fit. The system returned to six departments in 1858 when the Department of Utah was created in January, and the Department of the Pacific split into the Departments of California and Oregon in September. *

Department of the East The Department of the East was a military administrative district established by the U.S. Army several times in its history. The first was from 1853 to 1861, the second Department of the East, from 1863 to 1873, and the last from 1877 to 1913. H ...

, 1853 – 17 August 1861 *

Department of the West The Department of the West, later known as the Western Department, was a major command ( Department) of the United States Army during the 19th century. It oversaw the military affairs in the country west of the Mississippi River to the borders of C ...

, 1853 – 3 July 1861 *

Department of Texas The Department of Texas was a military department of the United States Army that existed from 1850 to 1861, and again from 1865 to 1866, from 1870 to 1913 and during the First World War. It was subordinate to the Military Division of the Missouri. ...

, 1853 – 22 April 1861 *

Department of the Pacific The Department of the Pacific or Pacific Department was a major command ( Department) of the United States Army from 1853 to 1858. It replaced the Pacific Division, and was itself replaced by the Department of California and the Department of O ...

, 1853 – September 13, 1858; 15 January 1861 – 27 June 1865 *

Department of New Mexico The Department of New Mexico was a Department (United States Army), department of the United States Army during the mid-19th century. It was created as the 9th Department, a geographical department, in 1848 following the successful conclusion of th ...

, 1853 – 27 June 1865 * Department of Utah, 30 June 1857 – 3 July 1861 *

Department of the Platte The Department of the Platte was a military administrative district established by the U.S. Army on March 5, 1866, with boundaries encompassing Iowa, Nebraska, Dakota Territory, Utah Territory and a small portion of Idaho. With headquarters in Om ...

, 4 April 1858 – 16 May 1859 *

Department of California The Department of California was an administrative department of the United States Army. The Department was created in 1858, replacing the original Department of the Pacific, and it was ended by the reorganizations of the Henry L. Stimson Plan i ...

, 13 September 1858 – 15 January 1861 *

Department of Oregon The Department of Oregon was one of two Army Departments created September 13, 1858, replacing the original Department of the Pacific and was composed of the Territories of Washington and Oregon, except the Rogue River and Umpqua Districts, which ...

, 13 September 1858 – 15 January 1861

1861–1865 Civil War

During the

American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...

, a department was a geographical command within the Union's military organization, usually reporting directly to the

. Many of the Union's departments were named after rivers, such as the

Department of the Potomac The Army of the Potomac was the principal Union Army in the Eastern Theater of the American Civil War. It was created in July 1861 shortly after the First Battle of Bull Run and was disbanded in June 1865 following the surrender of the Confedera ...

and the

Department of the Tennessee Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...

. The geographical boundaries of such departments changed frequently, as did their names. As the armies became larger Departments began to be subordinated to

Military Division A division is a large military unit or formation, usually consisting of between 6,000 and 25,000 soldiers. In most armies, a division is composed of several regiments or brigades; in turn, several divisions typically make up a corps. Historic ...

s, and the Departments were often sub divided into

Districts A district is a type of administrative division that, in some countries, is managed by the local government. Across the world, areas known as "districts" vary greatly in size, spanning regions or counties, several municipalities, subdivisions o ...

and from 1862,

Subdistrict A subdistrict or sub-district is an administrative division that is generally smaller than a district. Equivalents * Administrative posts of East Timor, formerly Portuguese-language * Kelurahan, in Indonesia * Mukim, a township in Brunei, In ...

s. Much information on Civil War departments can be found in Eicher & Eicher, ''Civil War High Commands''. *

Union Army Divisions, Departments and Districts During the American Civil War, a department was a geographical command within the Union's military organization, usually reporting directly to the War Department. Many of the Union's departments were named after rivers or other bodies of water, suc ...

1865–67

Military Division of the Atlantic Military Division of the Atlantic, was one of the military divisions of the U. S. Army created by GENERAL ORDERS No. 118. on June 27, 1865 at the end of the American Civil War. President Andrew Johnson directed that the United States was to be divid ...

, 1865–66 **

, 1865–73; independent 1866–68 ** Middle Military Department, 1866 **

Department of North Carolina The Department of Virginia and North Carolina was a United States Military department encompassing Union-occupied territory in the Confederate States during the Civil War. In 1863 it was formed by the merging of two previously existing department ...

, 1865–66; to Department of the Carolinas **

Department of South Carolina Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...

, 1865–66; to Department of the Carolinas **

Department of the Carolinas Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...

, May 1866; renamed

Department of the South The Department of the South was a military department of the United States Army that existed in several iterations in the 19th century during and after the American Civil War. 1862–65 After the first 11 months of the American Civil War, startin ...

, June 1866; to Second Military District **

Department of Virginia The Department of Virginia and North Carolina was a United States Military department encompassing Union-occupied territory in the Confederate States during the Civil War. In 1863 it was formed by the merging of two previously existing departmen ...

, 1865–66; to First Military District * Military Division of the Tennessee, 1865–67 ** Department of Alabama, 1865–66 ** Department of Georgia, 1865–66 ** Department of the South, 1866; to Third Military District ** Department of Kentucky, 1865–66 ** Department of Mississippi, 1865–66; to Fourth Military District ** Department of Tennessee, 1865–66 ** Department of the Cumberland, 1866 ** District of Tennessee, 1866 *** Sub-district of Tennessee, 1866 *

Military Division of the Missouri The Military Division of the Missouri was an administrative formation of the United States Army that functioned through the end of the American Civil War and the Indian Wars that continued after its conclusion. It was created by the War Departmen ...

, 1865; to Military Division of the Missouri **

Department of Arkansas The Department of the Arkansas was a territorial department of the United States Army during the American Civil War. History The Department of the Arkansas was created on January 6, 1864, to consist of Union occupied Arkansas, except Fort Smith. F ...

, 1865; to Military Division of the Gulf **

Department of the Missouri The Department of the Missouri was a command echelon of the United States Army in the 19th century and a sub division of the Military Division of the Missouri that functioned through the Indian Wars. History Background Following the successful ...

, 1865; to Military Division of the Mississippi **

Department of the Northwest The Department of the Northwest was an U.S. Army Department created September 6, 1862 to put down the Sioux uprising in Minnesota. Major General John Pope was made commander of the Department. At the end of the Civil War the Department was rede ...

, 1865; merged into Department of the Missouri *

Military Division of the Mississippi The Military Division of the Mississippi was an administrative division of the United States Army during the American Civil War that controlled all military operations in the Western Theater from 1863 until the end of the war. History The Divisio ...

, 1865–66 **

Department of the Ohio The Department of the Ohio was an administrative military district created by the United States War Department early in the American Civil War to administer the troops in the Northern states near the Ohio River. 1st Department 1861–1862 Genera ...

, 1865–66 **

, 1865–66; to Military Division of the Missouri **

, 1866; to Military Division of the Missouri *

Military Division of the Gulf A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...

, 1865–66 **

, 1865; to Military Division of the Mississippi **

Department of Louisiana Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...

, 1865–66; to Fifth Military District **

Department of Florida Department of Florida, was the military administrative department established by the Union Army. The Department of Florida was established on April 13, 1861 to defend and administer the few remaining Federal installations remaining in Florida. Fo ...

, 1865–66; to Third Military District ** Department of Mississippi, 1865; to Military Division of the Tennessee *

Military Division of the Pacific The Military Division of the Pacific was a major command ( Department) of the United States Army during the late 19th century. Formation On July 27, 1865 the Military Division of the Pacific was created under Major General Henry W. Halleck, replaci ...

, 1865–68, Division of the Pacific 1869–91 **

Department of the Columbia The Department of the Columbia was a major command ( Department) of the United States Army during the 19th century. Formation On July 27, 1865 the Military Division of the Pacific was created under Major General Henry W. Halleck, replacing the Dep ...

, 1865–1913 **

, 1865–1913 *** Military District of Alaska, 18 October 1867 – 18 March 1868 **

Department of Alaska Department of Alaska was the designation for the government of Alaska from its purchase by the United States of America in 1867 until its organization as the District of Alaska in 1884. During the department era, Alaska was variously under ...

, 18 March 1868 – 1 July 1870; merged into Department of the Columbia *

, 1866–91 **

, 1866–67; to Fourth Military District **

Department of Dakota A subdivision of the Division of the Missouri, the Department of Dakota was established by the United States Army on August 11, 1866, to encompass all military activities and forts within Minnesota, Dakota Territory and Montana Territory. The Depar ...

, 1866–91 **

, 1871–80

Military Reconstruction from 22 March 1867

First Military District The First Military District of the U.S. Army was one of five temporary administrative units of the U.S. War Department that existed in the American South. The district was stipulated by the Reconstruction Acts during the Reconstruction period f ...

, 1867–70 (Virginia) *

Second Military District The Second Military District of the U.S. Army was one of five temporary administrative units of the U.S. War Department that existed in the American South. The district was stipulated by the Reconstruction Acts during the Reconstruction period foll ...

, 1867–68 (North Carolina and South Carolina) *

Third Military District The Third Military District of the U.S. Army was one of five temporary administrative units of the U.S. War Department that existed in the American South. The district was stipulated by the Reconstruction Acts during the Reconstruction period follo ...

, 1867–68 (Georgia, Alabama and Florida) *

Fourth Military District The Fourth Military District of the U.S. Army was one of five temporary administrative units of the U.S. War Department that existed in the American South. The district was stipulated by the Reconstruction Acts during the Reconstruction period foll ...

, 1867–70 (Arkansas and Mississippi) *

Fifth Military District The Fifth Military District of the U.S. Army was one of five temporary administrative units of the U.S. War Department that existed in the American South from 1867 to 1870. The district was stipulated by the Reconstruction Acts during the Reconstru ...

, 1866–70 (Texas and Louisiana) * Military District of Georgia, 1870–71

1868–1904

Division of the Atlantic Division or divider may refer to: Mathematics *Division (mathematics), the inverse of multiplication *Division algorithm, a method for computing the result of mathematical division Military *Division (military), a formation typically consisting ...

, 1868–91 ** Department of the East, 1868–73 ** Department of the Lakes, 1868–73 ** Department of Washington, 1868–69 ** 1st Military District, 1869–70 (Virginia) ** Department of Virginia, 1870 ** Department of the South, 1876–83 ** Department of the Gulf, 1877–78 **

, 1877–91 * Division of the South, 1869–76 ** Department of the Cumberland, 1869–70 ** Department of the Gulf, 1871–75 ** Department of Louisiana, 1869–70 ** Department of the South, 1869–76 ** Department of Texas, 1870–71 ** 4th Military District, 1869–70 (Arkansas and Mississippi) ** District of Baton Rouge, 1876 ** 1st Subdistrict of Georgia, 1870–71 * Division of the Pacific, 1869–91 ** Department of Alaska, 1869–70 ** District of Arizona, 1869–70 ** District of the Humboldt, 1869 ** Sub-district of Southern Arizona, 1869–70 **

Department of Arizona The Department of Arizona was a military department of the United States Army that existed from 1870 to 1893. It was subordinate to the Military Division of the Pacific The Military Division of the Pacific was a major command ( Department) of the ...

, 1870–91 ** Department of California, 1870–91 ** Department of the Columbia, 1870–91 *

, 1876–83 ** Fort Johnson, NC, 1876–81 *

, 1881 **

, 1881 * Department of Texas, 1882–1904 * Department of the East, 1891–1904 * Department of the Platte, 1891–98 * Department of the Missouri, 1891–1904 * Department of Dakota, 1891–1904 * Department of Arizona, 1891–1893 * Department of California, 1891–1904 * Department of the Columbia, 1891–1904 * Department of Colorado, 1893–1904 *

, 1900–01

1898–99 Spanish–American War, Philippine Insurrection, Moro Rebellion

Department of the Lakes The Department of the Lakes was a military department of the United States Army that existed from 1866 to 1873 and again from 1898 to 1913. It was subordinate to the Military Division of the Atlantic and comprised posts in the Midwestern United Sta ...

, 1898–1913 *

Department of the Gulf The Department of the Gulf was a command of the United States Army in the nineteenth and early twentieth centuries and of the Confederate States Army during the Civil War. History United States Army (Civil War) Creation The department was cons ...

, 1898–99 * Department of California, 1898 ** Military District of Hawaii, 22 Sep – 7 November 1898 *

and 8th Army Corps, 1898 – 20 March 1900 * Division of the Philippines, 20 March 1900 – 1911 ** Northern Luzon, 1900–02 ** Department of Southern Luzon, 1900–01 ** Department of Visayas, 1900–11 ** Department of Mindanao and Jolo, 1900–14 ** Department of North Philippines, 1901–02 ** Department of South Philippines, 1901–02 ** Department of Luzon, 1902–14

1900s

1904–1911

The Army Departments were reorganized under new Divisions until 1907, when the Division echelon was disbanded. * Atlantic Division, 1903–07 ** Department of the East, 1903–13 ** Department of the Gulf, 1904–13 * Northern Division, 1904–07 ** Department of Dakota, 1904–11 ** Department of the Lakes, 1904–11 ** Department of the Missouri, 1904–07 *

Southwestern Division The United States Army Corps of Engineers Southwestern Division (SWD) is one of the eight permanent divisions of the Army organization, providing civil works and military water resource services and infrastructure. It also supports economically ...

, 1904–07 ** Department of Colorado, 1904–11 ** Department of Texas, 1904–13 * Pacific Division, 1904–07 ** Department of California, 1904–13 ***

District of Hawaii The United States Attorney for the District of Hawaii — also known as the United States Attorney and U.S. Attorney — is the chief law enforcement officer representing the federal government in the United States District Court for the Di ...

, 1910–1911 ** Department of the Columbia, 1904–13

Western Division (United States Army) 1911–1913

The Departments where again organized under new Divisions. * Eastern Division, 1911–13 ** Department of the East, 1911–13 ** Department of the Gulf, 1911–13 * Central Division, 1911–13 ** Department of the Lakes, 1911–13 ** Department of the Missouri, 1911–13 ** Department of Texas, 1911–13 * Western Division, 1911–13 ** Department of California, 1911–13 ** Department of the Columbia, 1911–13 ** District of Hawaii, 1911–13 * Philippines Division, 1911–1913 ** Department of Mindanao and Jolo, 1911–14 ** Department of Luzon, 1911–14

" Stimson Plan" 1913 – 1 May 1917

, 1913–1920 * Southern Department, 1913–1920 *

Central Department Central () is a department in Paraguay. The capital is Areguá. With 2,243,792 inhabitants, it is the most populated and the smallest of the 17 departments of Paraguay. Boundaries *North: the departments of Cordillera and Presidente Hayes *Wes ...

, 1913–1920 *

Hawaiian Department Hawaiian may refer to: * Native Hawaiians, the current term for the indigenous people of the Hawaiian Islands or their descendants * Hawaii state residents, regardless of ancestry (only used outside of Hawaii) * Hawaiian language Historic uses ...

, 1913–1920 *

, 1913–1942 ** Department of Mindanao and Jolo, 1913–14 ** Department of Luzon, 1913–14 * North Atlantic, South Atlantic, and Pacific Coast Artillery Districts

1 May 1917 – 1920

* Northeastern Department ** Northeastern Coast Artillery District * Eastern Department ** Eastern Coast Artillery District * Southeastern Department ** Southeastern Coast Artillery District * Southern Department ** Southern Coast Artillery District * Central Department * Western Department ** Western Coast Artillery District *

Panama Canal Department The Panama Canal Department was a department (geographical command) of the United States Army, responsible for the defense of the Panama Canal Zone between 1917 and 1947. First U.S. Army presence The Isthmian Canal Commission and the Panama Can ...

, 26 June 1917 – 1920 ** Panama Coast Artillery District, 26 June 1917 – 1920

References

{{reflist
U.S. Army Order of Battle 1919–1941, Volume 1. The Arms: Major Commands and Infantry Organizations(chapter 2)

Departments and districts of the United States Army