Apart from the general purpose of keeping inmates contained, however, Civil War prisons had little in common with their modern counterparts. They were typically nothing more than several dozen acres enclosed by a tall wooden wall.
Prisoners pieced together their shelters, called "shebangs," from a patchwork of blankets, scraps and sticks. Rations were meager handfuls of rancid grain, maybe a few beans or peas.
Poor planning by both North and South meant that overcrowding was rampant. The most notorious Confederate prison, in Andersonville, Ga., was built to contain 10,000 men, but by July 1864 it contained 32,000.
It is estimated that 13,000 Union prisoners died there from a combination of starvation, diseases such as scurvy and malaria, and exposure to the elements.
When Union Gen. William T. Sherman razed Atlanta, Confederate forces knew Andersonville would be an inviting target. Hastily, they built a new prison in Millen, Ga., and named it Camp Lawton.
Its 15-foot pine-log walls enclosed 42 acres, making it the largest Civil War prison in size. It must have seemed a paradise at first for the Andersonville prisoners, who had been jammed into 26 acres.
A freshwater stream divided the small valley that Camp Lawton was nestled in, and rations were somewhat better at first because the countryside had yet to be scoured of food.
Many prisoners were too weak from their previous incarceration, though, to appreciate it. The camp was open scarcely three months, but in that time nearly 500 prisoners died from disease.
Inside the prison, a low fence set 30 feet from the walls created a "dead line" that prisoners couldn't cross. Guards kept watch from "pigeon roosts" set along the walls.
Water for cooking was fetched from upstream; downstream was used as a latrine. The only structures inside the building besides the shebangs were a bridge across the stream and a sutler's cabin.
Outside the walls were a guards' camp, a hospital, some administrative buildings built of logs, and two burial grounds for prisoners.
The only existing record of prisoners and guards shows there were 10,299 prisoners. Of those, 349 had enlisted in the Confederate Army, 486 were deceased and 285 were working at the prison as administrators, cobblers or butchers.
A sick-prisoner exchange in mid-November 1864 at the port of Savannah included many Camp Lawton inmates. Others were sent to prisons in South Carolina or Blackshear, Ga., a scant six weeks after the first prisoners arrived at Camp Lawton.
The exact location of Camp Lawton was lost to time until 2010, when archaeologists at Georgia Southern University found it at Magnolia Springs State Park.
Because it was previously undiscovered, archaeologists have found a wealth of undisturbed artifacts. Many were likely left behind by the guards and prisoners in the hasty evacuation that precipitated Sherman's arrival.
"There will be work out there for years and years -- 30 to 40 years," Kevin Chapman, a Georgia Southern University graduate student who helped launch a dig at Camp Lawton, said last year.