XXI Corps was a

corps Corps (; plural ''corps'' ; from French , from the Latin "body") is a term used for several different kinds of organization. A military innovation by Napoleon I, the formation was first named as such in 1805. The size of a corps varies great ...

of the

Union Army During the American Civil War, the Union Army, also known as the Federal Army and the Northern Army, referring to the United States Army, was the land force that fought to preserve the Union (American Civil War), Union of the collective U.S. st ...

during the

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

. It served as part of William S. Rosecrans's

Army of the Cumberland The Army of the Cumberland was one of the principal Union armies in the Western Theater during the American Civil War. It was originally known as the Army of the Ohio. History The origin of the Army of the Cumberland dates back to the creation ...

and was in existence from January 9th to October 1863. After the

Battle of Stone's River The Battle of Stones River, also known as the Second Battle of Murfreesboro, was a battle fought from December 31, 1862, to January 2, 1863, in Middle Tennessee, as the culmination of the Stones River Campaign in the Western Theater of the Amer ...

, General Rosecrans reorganized the "wings" of his army into three corps. The left wing, under

Thomas L. Crittenden Thomas Leonidas Crittenden (May 15, 1819 – October 23, 1893) was a lawyer, politician, and Union general during the American Civil War. Early life Crittenden was born in Russellville, Kentucky, the son of U.S. Senator John J. Crittenden, who ...

, became the XXI Corps. Taking part in the Tullahoma Campaign, the XXI Corps was heavily engaged at

Chickamauga Chickamauga may refer to: Entertainment * "Chickamauga", an 1889 short story by American author Ambrose Bierce * "Chickamauga", a 1937 short story by Thomas Wolfe * "Chickamauga", a song by Uncle Tupelo from their 1993 album ''Anodyne (album), Ano ...

on September 19–20, 1863, where it was nearly destroyed. It was Rosecrans' mistaken decision to pull Thomas Wood's division of this corps to support George Thomas's

XIV Corps 14 Corps, 14th Corps, Fourteenth Corps, or XIV Corps may refer to: * XIV Corps (Grande Armée), a unit of the Imperial French Army during the Napoleonic Wars * XIV Corps (German Empire), a unit of the Imperial German Army prior to and during World ...

that resulted in General

James Longstreet James Longstreet (January 8, 1821January 2, 1904) was one of the foremost General officers in the Confederate States Army, Confederate generals of the American Civil War and the principal subordinate to General Robert E. Lee, who called him his ...

's breakthrough against the Union center. It should be added, though, that elements of XXI Corps, most notably William J. Palmer's division, aided Thomas in his successful rearguard action on Snodgrass Hill. Along with the remnants of XX Corps, the corps reorganized into IV Corps shortly after the battle.

External links

XXI Corps history
{{AmericanCivilWar-unit-stub 21 Military units and formations established in 1863 1863 establishments in the United States