Early in 1862, the army fought its first battle at Mill Springs, although only the 1st Division, commanded by Brig.

The battle Thomas foresaw occurred on October 8, 1862, west of Perryville, Kentucky.

Confederate General Braxton Bragg had marched into Kentucky to recruit soldiers and take the state from the Union.

On March 19, 1863, two divisions of the IX Corps under Maj. Gen. John G. Parke had been ordered from Virginia to Burnside's department.

The IX Corps was soon transferred to Mississippi in June to participate in the siege of Vicksburg but was returned to the Army of the Ohio in August.

Reunited with the IX Corps and the addition of a cavalry division, Burnside moved to Knoxville, Tennessee.

Maj. Gen. John G. Foster replaced Burnside as commander of the Army and Department of the Ohio on December 9.

The XXIII Corps was ordered to North Carolina and only Cox's division was present for the Battle of Wilmington.

It was not until March 1865 that the rest of the XXIII Corps landed at New Bern, North Carolina.

Livermore, Thomas L., Numbers and Losses in the American Civil War 1861–1865, New York, 1901, p. 95, cited in McDonough, James Lee, War in Kentucky, University of Tennessee Press, 1994, pp 289–290.