XVII Corps was a corps of the Union Army during the American Civil War. It was organized December 18, 1862 as part of Ulysses S. Grant's Army of the Tennessee. It was most notably commanded by Maj. Gen. James B. McPherson and Maj. Gen. Francis P. Blair II, and served in the Western Theater.

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."