After the surrender of Confederate forces at Vicksburg on July 4, 1863, the various companies of the 1st Light Artillery were dispersed and saw action across the Western theater of the American Civil War, although they never operated as a combined regiment.

A study of Company G of the 1st Mississippi Light Infantry found that only 20.5% of the men were farmers, whereas 26.9% were students, 7.8% were clerks, and the rest had non-farm professions such as artisan and craftsman.

"[4] Company H, known as the Conner Battery, commanded by Captain George Ralston was assigned to the Trans-Mississippi department in September 1862 and operated independently of the rest of the regiment.

[2] Companies B, F, & K were deployed across the Mississippi River in Louisiana and took part in the Siege of Port Hudson and the Battle of Plains Store.

General William Wing Loring described the actions of the 1st Mississippi Light Artillery in this battle: "It was here that we witnessed a scene ever to be remembered, when the gallant Withers and his brave men, with their fine park of artillery, stood unflinchingly amid a shower of shot and shell the approach of an enemy in overwhelming force, after his supports had been driven back, and trusting that a succoring command would arrive in time to save his batteries, and displaying a degree of courage and determination that calls for the most unqualified admiration.

"[5] During this battle, Confederate General Lloyd Tilghman was directing the fire of Company G of the 1st Mississippi Light Artillery when he was hit by a Union shell and killed.

[2] Following the defeat at Champion Hill, a detachment of the regiment fought at the Battle of Big Black River Bridge, with several killed and 3 guns lost.