Army of the Tennessee

The Army of the Tennessee was a Union army in the Western Theater of the American Civil War, named for the Tennessee River. A 2005 study of the army states that it "was present at most of the great battles that became turning points of the war—Fort Donelson, Vicksburg, and Atlanta" and "won the decisive battles in the decisive theater of the war."

It appears that the term "Army of the Tennessee" was first used within the Union Army in March 1862, to describe Union forces perhaps more properly described as the "Army of West Tennessee"; these were the troops under the command of Maj. Gen. Ulysses S. Grant in the Union's District of West Tennessee. This article also covers Grant's 1861–1862 commands – the District of Southeast Missouri and the District of Cairo – because the troops Grant led in the Battle of Belmont and the Henry-Donelson campaign during that period became the nucleus of the Army of the Tennessee. In April 1862, Grant's troops survived a severe test in the bloody Battle of Shiloh. Then, during six months marked by discouragement and anxiety for Grant, his army first joined with two other Union armies to prosecute the relatively bloodless Siege of Corinth and then strained to hold Union positions in Tennessee and Mississippi. In October 1862, Grant's command was reconfigured and elevated to departmental status, as the Department of the Tennessee; the title of his command was thus officially aligned with that of his army. Grant commanded these forces until after his critically important victory at Vicksburg on July 4, 1863. Grant was then tasked with command of the Military Division of the Mississippi, overseeing this army and additional Union armies.