The South was at a relative disadvantage to the North for deployment of artillery. The industrial North had far greater capacity for manufacturing weapons, and the Union blockade of Southern ports prevented many foreign arms from reaching the Southern armies. The Confederacy had to rely to a significant extent on captured Union artillery pieces (either on the battlefield or by capturing armories, such as Harpers Ferry); it is estimated that two thirds of all Confederate field artillery was captured from the Union. The Confederate cannons built in the South often suffered from the shortage of quality metals and shoddy workmanship. Another disadvantage was the quality of ammunition. The fuses needed for detonating shells and cases were frequently inaccurate, causing premature or delayed explosions. All that, coupled with the Union gunners' initial competence and experience gained as the war progressed, led Southern forces to dread assaults on Northern positions backed up by artillery. A Southern officer observed, "The combination of Yankee artillery with Rebel infantry would make an army that could be beaten by no one."
Confederate batteries usually consisted of four guns, in contrast to the Union's six. This was a matter of necessity, because guns were always in short supply. And, unlike the Union, batteries frequently consisted of mixed caliber weapons. Confederate batteries were generally organized into battalions (versus the Union brigades) of four batteries each, and the battalions were assigned to the direct support of infantry divisions. Each infantry corps was assigned two battalions as an Artillery Reserve, but there was no such Reserve at the army level. The chief of artillery for Robert E. Lee's Army of Northern Virginia, Brig. Gen. William N. Pendleton, had considerable difficulty massing artillery for best effect because of this organization.