The Army of Mississippi (also known as the Army of the West) was organized on March 5, 1862 under the command of Gen. P. G. T. Beauregard and served in the Western Theater. On March 13, 1862 units of the Army of Pensacola were added to it, and it was consolidated with the Army of Central Kentucky and the Army of Louisiana on March 29, 1862. It was later commanded by Gen. Albert Sidney Johnston, Gen. Braxton Bragg, Maj. Gen. William J. Hardee, and Lt. Gen. Leonidas Polk. It was renamed the Army of Tennessee on November 20, 1862. (Wiki)

Read more about Confederate States of America. Army. Army of Mississippi (1862 Mar. 5-Nov. 20)