18th Heavy Artillery Battalion [often called the Siege Train Artillery Battalion] was organized during the spring of 1862 with three companies. Many of the men were from Charleston. It was assigned to the Department of South Carolina, Georgia, and Florida, and fought at Fort Sumter, Grimball's Landing, Battery Wagner, James Island, and John's Island. In June, 1864, Company C was transferred to Pegram's Battalion of Artillery, Army of Northern Virginia and was active in the Petersburg siege. That December it returned to the battalion which later served as infantry in the Army of Tennessee. It surrendered on April 26, 1865. The field officers were Majors Charles Alston, Jr. and Edward Manigault.