This regiment was organized in May 1862 at Mobile, and remained there till December. It then moved to Vicksburg, and took part in the operations on Deer Creek. While in that region, it was brigaded with the Thirty-seventh, and Forty-second Alabama, and Second Texas, under Gen. Moore. Four companies were placed in Fort Pemberton, and were from there transferred to Gen. Bragg's army, and fought at Chicamauga.
The other companies of the Fortieth were part of the garrison of Vicksburg, suffered severely, and were there captured. The regiment was united near Mission Ridge, and took part in that battle, and at Look-out Mountain, but with light loss. Having passed the winter at Dalton, where Gen. Baker took command of the brigade, the Fortieth took part in the campaign from there to Atlanta, losing largely, especially at New Hope.
When the army marched back to Tennessee, in company with the other regiments of Baker's brigade, the Fortieth was sent to Mobile, and was on garrison duty there for some months. In January 1865, the regiment proceeded with the remainder of the army to North Carolina, and shared in the operations, fighting at Bentonville with severe loss. Consolidated with the Nineteenth and Forty-sixth, the Fortieth was shortly after surrendered at Yadkin River bridge.