Andersonville, or Camp Sumter as it was officially known, was the largest of several military prisons established during the Civil War. It was built in 1864 after Confederate leaders decided to move the many Union prisoners in Richmond, Virginia, to a location away from the war. A site was needed where the prisoners could be guarded by fewer men, there would be less chance of military raids to free them, and food would be more abundant. The town of Andersonville was located on a railroad line approximately 65 miles southwest of Macon, Georgia. The village, near a small stream and in a remote agricultural area, seemed ideal. Construction of the 16 1/2 acre prison camp began in January 1864. Pine logs, 20 feet in length, were placed five feet deep in the ground to create a wooden stockade. In June 1864, the prison was enlarged to 26 1/2 acres. The prison proper was in the shape of a rectangle 1,620 feet long and 779 feet wide. Sentry boxes, or "pigeon roosts," were placed at 30 yard intervals along the top of the stockade. Along the interior of the stockade, 19 feet from the stockade wall, was a line of small wooden posts with a wood rail on top. This was the "deadline." Any prisoner who crossed the deadline could be shot by guards stationed in the sentry boxes. Small earthen forts around the exterior of the prison were equipped with artillery to put down disturbances within the compound and to defend against Union cavalry attacks.
The first prisoners arrived on February 25, 1864, while the stockade wall was still under construction. Small earthworks, equipped with artillery, overlooked the compound. Designed to hold 10,000 prisoners, the prison was soon overcrowded, holding 22,000 by June. Although the prison was enlarged, the number of prisoners continued to swell. By August 1864, more than 32,000 prisoners were confined at Andersonville.
Hindered by deteriorating economic conditions, an inadequate transportation system, and the need to concentrate all available resources on its own army, the Confederate government was unable to provide adequate housing, food, clothing, shelter, and medical care for its captives. These conditions, along with a breakdown of the prisoner exchange system, created much suffering and a high mortality rate. More than 45,000 Union soldiers were sent to Andersonville during the 14 months of the prison's existence. Of these, 12,912 died from disease, malnutrition, overcrowding, or exposure. They were buried in shallow trenches, shoulder to shoulder, in a crude cemetery near the prison.
In September 1864, when General William T. Sherman's forces occupied Atlanta, and a Union cavalry column threatened Andersonville's security, most of the prisoners were moved to other camps in Georgia and South Carolina. The prison operated on a much smaller scale for the remaining six months of the war.
Following the Confederate surrender in April 1865, Clara Barton, later founder of the American Red Cross, and Dorence Atwater, a former prisoner assigned as a parolee to keep burial records for prison officials, visited the cemetery at Andersonville to identify and mark the graves of the Union dead. During the war Atwater had labeled the soldiers by name and number after their deaths. Through Barton and Atwater's efforts, the cemetery was dedicated as Andersonville National Cemetery in August 1865.
Another important event that occurred after the war was the arrest and trial of Captain Henry Wirz, the commandant of the prison. Wirz was arrested and charged with conspiring to "impair and injure the health and destroy the lives of federal prisoners" and with "murder in violation of the laws of war." At his trial in Washington D.C., many former prisoners testified against him, vividly describing conditions at the prison. The former prisoners (and one who testified but was never actually a prisoner) blamed Wirz as the cause of their suffering. Historical documents, however, attest to the fact that prison officials attempted to acquire supplies for the prisoners but were severely hampered by the need to use supplies for the military and war effort. The question of whether or not Wirz could have done more to make life more bearable for the prisoners is still debated today. Was he simply a convenient scapegoat? Because of public outrage and indignation in the North over conditions at Andersonville, Captain Henry Wirz was found guilty of war crimes and was hanged on November 10, 1865. It has been said that Wirz was the last casualty of Andersonville.