The Army of the Tennessee was a Union army in the Western Theater of the American Civil War, named for the Tennessee River. It should not be confused with the similarly named Army of Tennessee, a Confederate army named after the State of Tennessee. 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.