page_title: Army of the Tennessee
section_title: Iuka and the Battle of Corinth
hierarchical_section_title: Army of the Tennessee / History / Iuka and the Battle of Corinth
caption_attribution_description: English: Portrait of Maj. Gen. Henry W. Halleck, officer of the Federal Army.
context_page_description: The Army of the Tennessee was a Union army in the Western Theater of the American Civil War, named for the Tennessee River.
  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. 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.
context_section_description: In July 1862, Lincoln summoned Henry Halleck to Washington to serve as general-in-chief; Halleck was not replaced as departmental commander, leading by September to the demise of the geographically broad Department of the Mississippi. One immediate result was that, on July 16, Halleck enlarged Grant's District of West Tennessee and included within it portions of Alabama and Mississippi, as well as the Army of the Mississippi, five divisions then under the command of Maj. Gen. William S. Rosecrans. Grant relocated his headquarters to Corinth (and later Jackson, Tennessee) to oversee his expanded responsibilities. He soon lost four divisions from this expanded command—that of George Thomas and three from Rosecrans's Army of the Mississippi—to Buell's Army of the Ohio; these losses shrank Grant's forces from approximately 80,000 men to less than 50,000. This threw Grant on the "defensive," simply trying to deploy his remaining forces to protect his own positions against threatening Confederate forces; Grant later described this as his "most anxious period of the war." It came to an end with victories led by General Rosecrans in the September Battle of Iuka and the more consequential October Battle of Corinth. Grant was nearby and coordinating with Rosecrans, but not on the field, for these two battles; Rosecrans fought Iuka with elements of his shrunken Army of the Mississippi, and Corinth with the addition of two divisions from the Army of the Tennessee. The victory at Corinth was sufficiently clear cut to relieve Grant "from any further anxiety for the safety of the territory within my jurisdiction."
  Soon thereafter, on October 16, Grant's geographical command was redefined and elevated to departmental status, becoming the Department of the Tennessee. This made the term "Army of the Tennessee" more official for his troops. Also in October, Don Carlos Buell lost command of the Army of the Ohio; his place went to Rosecrans, whose commands were christened the Department and the Army of the Cumberland. By an order dated December 18, but not fully implemented until somewhat later, Grant's Army of the Tennessee was organized into four corps—the XIII under John McClernand, the XV under W.T. Sherman, the XVI under Stephen A. Hurlbut, and the XVII under Maj. Gen. James B. McPherson. Each corps contained several divisions and detachments of artillery and cavalry. For illustrative purposes, the reported organization and strength of the Army of the Tennessee as of April 30, 1863, when it numbered approximately 150,000 in total, can be seen in the Official Records.
caption: General Henry Wager Halleck
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