The deadliest ground of the American Civil War lies in rural southwest Georgia.

It is not a battlefield.

It's a small area, 26 ½ acres, roughly half the size of Hartford's Bushnell Park. There, over the course of 14 months beginning in February 1864, nearly 13,000 Union prisoners of war died, principally from disease, starvation and maltreatment.

Known to history as Andersonville Prison, after the nearby village, Camp Sumter was a place of horror and despair. More than 300 Connecticut soldiers perished there, and today lay buried in the Andersonville National Cemetery, established in July 1865.

How the nation learned about the conditions inside the stockade, and why most individual graves are marked by name, was largely due to the efforts of two Andersonville survivors from Connecticut — Sgt. Maj. Robert H. Kellogg of Wethersfield and Pvt. Dorence Atwater of Terryville.

Like many prisoners, Kellogg kept a diary during his captivity. It became the basis for a book, published in Hartford in 1865, that provided readers with a first-person account of conditions inside Andersonville and other Southern prisons.

Its publication briefly thrust Kellogg into the national spotlight, and he testified for the prosecution in the trial of the camp commander, Capt. Henry Wirz.

Decades later, he would speak for all fellow survivors at the 1907 dedication of the Connecticut monument at the Andersonville cemetery. A copy of the memorial's statue — known as the Andersonville Boy — stands outside the Connecticut Capitol.

Atwater, as a teenager, assisted the camp surgeon in recording prisoner deaths. Unbeknownst to his captors, and at considerable personal peril, he secretly copied the camp's official roll and smuggled it out of camp after being paroled.

He returned to Georgia in the summer of 1865 with his friend Clara Barton, the founder of the American Red Cross, and helped the U.S. Army match individual graves with their occupants, then notified family members of the fate of their loved ones. The Atwater death roll, containing nearly 13,000 names, was published by Horace Greeley in 1866.

"We go as far to say here he was single most important prisoner to be held here,'' said Eric Leonard, chief of interpretation and education at the National Park Service Andersonville National Historic Site.

Neither Kellogg nor Atwater (despite his modest memorial in his hometown of Plymouth), is much remembered today.

Hell On Earth

The deplorable treatment of prisoners of war — both Union and Confederate — remains one of the Civil War's most shameful legacies.

Of the 194,000 Union prisoners, more than 30,000 died in Southern prisons; 26,000 of 214,000 Confederate POWs lost their lives in the North.

Most of the deaths occurred during the war's final two years. Formal prisoner exchanges were halted in mid-1863 because of the Confederacy's refusal to return black POWs, and the South's increasingly desperate manpower shortage gave Union military leaders little incentive to resume the exchanges.

By early summer 1864, Lt. Gen. Ulysses S. Grant's bloody overland campaign to take Richmond, and Maj. Gen. William T. Sherman's campaign to capture Atlanta, had swelled prison rolls on both sides.

The prison at Andersonville, located in an agricultural region with pine woods and fresh-flowing streams, was supposed to relieve overcrowding at other Confederate facilities. Designed to hold 10,000 captives, it opened on Feb. 1, 1864, with early occupants transferred from other prison hospitals.

The prison had already established a less-than-savory reputation by the time Kellogg and other men from the 16th Connecticut Volunteer Infantry Regiment were led through the stockade gates on May 3, 1863.

Nearly the entire regiment, 459 men, had been taken prisoner on April 20 at Plymouth, N.C. Before surrendering, the men had cut up their regimental flag and distributed the pieces among themselves. After the war, the surviving fragments were restitched into the banner that today hangs in the Hall of Flags in the state Capitol.