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."

The Battle of Shiloh, also known as the Battle of Pittsburg Landing, was a major battle in the American Civil War fought on April 6–7, 1862. The fighting took place in southwestern Tennessee, which was part of the war's Western Theater. The battlefield is located between a small, undistinguished church named Shiloh and Pittsburg Landing on the Tennessee River. Two Union armies combined to defeat the Confederate Army of Mississippi. Major General Ulysses S. Grant was the Union commander, while General Albert Sidney Johnston was the Confederate commander until his battlefield death, when he was replaced by his second-in-command, General P. G. T. Beauregard.