The XVI Corps was organized on December 18, 1862 with Maj. Gen. Stephen A. Hurlbut in command. It had four divisions commanded respectively by William Sooy Smith (1st Division), Grenville Dodge (2nd Division), Nathan Kimball (3rd Division) and Jacob G. Lauman (4th Division). These divisions were assigned to garrison duty in the vicinity of Memphis, Tennessee, LaGrange, Tennessee and Corinth, Mississippi. With the Army of the Tennessee besieging Vicksburg, Maj. Gen. Ulysses S. Grant gathered reinforcements from the surrounding areas. The divisions of Smith, Kimball and Lauman were ordered to Vicksburg on June 12. This detachment was led by Maj. Gen. Cadwallader C. Washburn. Hurlbut and Dodge remained on garrison duty in Tennessee during this time. After the fall of Vicksburg, Smith's division was attached to the IX Corps and Lauman's division was attached to the XIII Corps during Maj. Gen. William T. Sherman's expedition to Jackson, Mississippi.