Department (United States Army)


Department is an organizational term used by the U.S. Army, mostly prior to World War I, 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 Areas. However, the Hawaiian, Panama Canal, and Philippine Departments retained their old names. In 1939, the Puerto Rican Department was created and in May 1941 the Panama Canal and Puerto Rican Departments were combined as the Caribbean Defense Command, 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 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At the end of the War of 1812, Military districts were superseded by ten Military Departments, divided equally between Divisions of the North and South, 17 May 1815.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, 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, 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.
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

    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

    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
  • Pacific Division, 1848–53,
  • * 10th Military Department, 1846–1853
  • * 11th Military Department, 1848–1853

    1853–1861

After 31 October 1853 the division echelon was eliminated and the six western departments consolidated into four, 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.
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, such as the Department of the Potomac and the Department of the Tennessee. The geographical boundaries of such departments changed frequently, as did their names. As the armies became larger Departments began to be subordinated to Military Divisions, and the Departments were often sub divided into Districts and from 1862, Subdistricts. Much information on Civil War departments can be found in Eicher & Eicher, Civil War High Commands.
  • Union Army Divisions, Departments and Districts

    1865–67

  • Military Division of the Atlantic, 1865–66
  • * Department of the East, 1865–73; independent 1866–68
  • * Middle Military Department, 1866
  • * Department of North Carolina, 1865–66; to Department of the Carolinas
  • * Department of South Carolina, 1865–66; to Department of the Carolinas
  • * Department of the Carolinas, May 1866; renamed Department of the South, June 1866; to Second Military District
  • * Department of Virginia, 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, 1865; to Military Division of the Missouri
  • * Department of Arkansas, 1865; to Military Division of the Gulf
  • * Department of the Missouri, 1865; to Military Division of the Mississippi
  • * Department of the Northwest, 1865; merged into Department of the Missouri
  • Military Division of the Mississippi, 1865–66
  • * Department of the Ohio, 1865–66
  • * Department of Arkansas, 1865–66; to Military Division of the Missouri
  • * Department of the Missouri, 1865–66; to Military Division of the Missouri
  • * Department of the Platte, 1866; to Military Division of the Missouri
  • Military Division of the Gulf, 1865–66
  • * Department of Arkansas, 1865; to Military Division of the Mississippi
  • * Department of Louisiana, 1865–66; to Fifth Military District
  • * Department of Texas, 1865–66; to Fifth Military District
  • * Department of Florida, 1865–66; to Third Military District
  • * Department of Mississippi, 1865; to Military Division of the Tennessee
  • Military Division of the Pacific, 1865–68, Division of the Pacific 1869–91
  • * Department of the Columbia, 1865–1913
  • * Department of California, 1865–1913
  • ** Military District of Alaska, 18 October 1867 – 18 March 1868
  • * Department of Alaska, 18 March 1868 – 1 July 1870; merged into Department of the Columbia
  • Military Division of the Missouri, 1866–91
  • * Department of Arkansas, 1866–67; to Fourth Military District
  • * Department of Dakota, 1866–91
  • * Department of the Missouri, 1866–91
  • * Department of the Platte, 1866–91
  • * Department of Texas, 1871–80

    Military Reconstruction from 22 March 1867

  • First Military District, 1867–70
  • Second Military District, 1867–68
  • Third Military District, 1867–68
  • Fourth Military District, 1867–70
  • Fifth Military District, 1866–70
  • Military District of Georgia, 1870–71

    1868–1904

  • Division of the Atlantic, 1868–91
  • * Department of the East, 1868–73
  • * Department of the Lakes, 1868–73
  • * Department of Washington, 1868–69
  • * 1st Military District, 1869–70
  • * Department of Virginia, 1870
  • * Department of the South, 1876–83
  • * Department of the Gulf, 1877–78
  • * Department of the East, 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
  • * 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, 1870–91
  • * Department of California, 1870–91
  • * Department of the Columbia, 1870–91
  • Department of the South, 1876–83
  • * Fort Johnson, NC, 1876–81
  • Military Division of the Gulf, 1881
  • * Department of Arkansas, 1881
  • * Department of Texas, 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
  • Department of Alaska, 1900–01