The 3rd Maryland Battery was mustered in on January 14th, 1862 in Richmond, Virginia under the command of Captain Henry B. Latrobe. It was quickly ordered to Knoxville and served in East Tennessee and Kentucky. It moved to Mississippi in December, 1862 probably with Carter Stevenson's division. It campaigned in the Mississippi theatre and the Vicksburg campaign. A portion of the battery served on the Rebel boat Queen of the West. The rest of the battery served at Vicksburg until it surrendered with the fall of Vicksburg in July 1863 with 77 men. In September, 1863, the battery was reorganized in Tennessee but only for a short time under the command of Captain William L. Ritter. Early 1864, it was merged into Stephen's Georgia Battery.