Union Armies

Below are the Union field armies created during the war.

Eastern Theater

Army	Commanding General(s)	Fate
Army of the Shenandoah I (Jun 1861 - Aug 1861)	Robert Patterson	Most troops mustered out; some troops to the Dept. of the Shenandoah
Army of Occupation (Jun 1861 - Sep 1861)	George B McClellan – Jun 1861-Jul 1861 William S. Rosecrans – Jul 1861-Sep 1861	The army was merged into the Dept. of Western Virginia under William S. Rosecrans
Army of the Mountain Department (Mar 1862 - Jun 1862)	John C. Fremont	Merged into the Army of Virginia as the I Corps
Army of Virginia (Jun 1862 - Sep 1862)	John Pope	Merged into the Army of the Potomac
Army of the Potomac (Aug 1861 - Jun 1865)	George B McClellan – Aug 1861-Nov 1862 Ambrose E Burnside – Nov 1862-Jan 1863 Joseph Hooker – Jan-Jun 1863 George G Meade – Jun-1863-Jun 1865
Army of Northeastern Virginia (Jul 1861 - Sep 1861)	Irvin McDowell	Some troops mustered out; most troops to the Military District of the Potomac
Army of the Shenandoah II (Jun 1864 - Jul 1864)	David Hunter	Most troops become the Army of the Kanawha; some troops fall under the Dept. of West Virginia
Army of the Kanawha (Jul 1864 - Aug 1864)	George Crook	Army renamed the Army of West Virginia
Army of West Virginia (Aug 1864 - Dec 1864)	George Crook	Army merged into Army of the Shenandoah III
Army of the Shenandoah III (Aug 1864 - Jun 1865)	Philip Sheridan - Aug 1864-Apr 1865 Alfred T. A. Torbert - Apr 1865-Jun 1865

Western Theater

Army	Commanding General(s)	Fate
Army of the Ohio (Nov 1861 - Oct 1862)	Don Carlos Buell	Renamed Army of the Cumberland Oct 1862
Army of the Mississippi (Feb 1862 - Oct 1862)	John Pope - Feb-Jun 1862 William S. Rosecrans - Jun-Oct 1862	Merged into Army of the Tennessee Oct 1862
Army of West Tennessee (Feb 1862 - Oct 1862)	Ulysses S. Grant	Renamed Army of the Tennessee Oct 1862
Army of the Mississippi II (Jan 1862)	John A. McClernand	Merged into Army of the Tennessee Jan 1862
Army of the Tennessee (Oct 1862 - Aug 1865)	Ulysses S. Grant
Army of the Cumberland (Oct 1862 - Aug 1865)	William S. Rosecrans - Oct 1862-Oct 1863 George H. Thomas - Oct 1863-Aug 1865
Army of the Ohio II (Apr 1863 - Aug 1865)	Ambrose E. Burnside
Army of the Gulf (Feb 1862 - Aug 1865)	Benjamin F Butler	Renamed Army of West Mississippi Feb 1865
Army of Georgia (Nov 1864 - Aug 1865)	Henry W. Slocum
Army of West Mississippi (Feb 1865 - Aug 1865)	Edward R.S. Canby

Trans-Mississippi Theater

Army	Commanding General(s)	Fate
Army of the West (Jul 1861 - Aug 1861)	Nathaniel Lyon	Some troops mustered out; troops form part of Western Army
Western Army (Army of the West) (Sep 1861 - Oct 1861)	John C. Fremont	Troops dispersed to other organizations
Army of Western Missouri (Dec 1861 - Feb 1862)	John Pope	Most troops sent to Army of Southwest Missouri
Army of Southwest Missouri (Army of the Southwest) (Dec 1861 - Dec 1862)	Samuel Curtis - Dec 1861-Aug 1862 Frederick Steele - Aug 1862-Oct 1862 Eugene Carr - Oct 1862-Nov 1862 Willis Gorman (temp.) - Nov 1862-Dec 1862	Troops dispersed to other armie and districts
Army of Kansas (Aug 1862 - Sep 1862)	James G. Blunt	Most troops sent to Army of Frontier; others to District of Kansas
Army of the Frontier (Oct 1862 - Aug 1863)	John Schofield - Oct 1862-Nov 1862 James G. Blunt - Nov 1862-Dec 1862 John Schofield - Dec 1862-Mar 1863 Francis Herron - Mar 1863-Aug 1863	Troops dispersed to Districts of the Missouri, Frontier and Border
Army Southeastern Missouri (Dec 1862 - Mar 1863)	John W. Davidson	Troops sent to XIII corps and District of Southeaster Missouri
Army of Arkansas (Jul 1863 - Aug 1865)	Frederick Steele - Jul 1863-Dec 1864 Joseph Reynolds - Dec 1864-Aug 1865
Army of the Border (Oct 1864 - Nov 1864)	Samuel R. Curtis	Kansas State Militia released; rest of troops with Alfred Pleaston and Department of Kansas

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