When large-scale fighting began in 1861, both the Union and Confederacy captured prisoners quickly, but neither side had a stable, formal exchange program. Early on, many captives were paroled (released after promising not to fight) or held in improvised facilities, setting the stage for later crises as prisoner numbers grew.
Union Gen. John A. Dix and Confederate Gen. D. H. Hill signed the Dix–Hill Cartel to standardize prisoner exchanges. The agreement set an exchange “scale” by rank and relied heavily on paroles, reducing the need to house large numbers of prisoners—at least temporarily.
The Union issued General Orders No. 100, known as the Lieber Code, to guide how Union forces should conduct war, including rules related to prisoners of war. It emphasized that exchanges were optional (a matter of “convenience”) and discussed retaliation as a limited tool rather than revenge—ideas that shaped later exchange disputes.
A Confederate policy shift classified captured Black Union soldiers differently from white prisoners of war, treating many as enslaved people to be returned to bondage rather than exchanged. This stance directly undermined the exchange system by making equal treatment—a core Union demand—impossible under Confederate policy.
President Abraham Lincoln issued General Order 252, tying prisoner exchange to equal treatment of Black and white Union soldiers. When the Confederacy refused, large-scale exchanges largely stopped, causing prisoner populations to rise sharply on both sides.
The Union established a large prison camp at Point Lookout, Maryland, to hold growing numbers of Confederate prisoners. Its rapid crowding became a warning sign of what would happen as exchanges slowed and prisons expanded across the country.
The Union built a prison camp at Rock Island Arsenal, Illinois, as part of a strategy to hold prisoners farther from active battle zones. It began receiving prisoners in December 1863, reflecting the shift from quick exchanges toward long-term confinement.
The Confederacy opened Camp Sumter near Andersonville, Georgia, to relieve overcrowded prisons nearer the front and major cities. The first Union prisoners arrived in late February 1864, and the camp soon became a central symbol of the prison crisis as numbers surged beyond intended capacity.
At Fort Pillow, Tennessee, Confederate troops overran a Union garrison that included many Black soldiers, and large numbers of Union defenders were killed. The event increased Union demands for equal prisoner treatment and reinforced how race and retaliation debates were tied to the exchange breakdown.
After taking overall command of Union armies, Ulysses S. Grant reaffirmed the existing policy of not resuming broad exchanges while the Confederacy refused equal treatment for Black prisoners. This decision helped drive the rapid expansion and overcrowding of prison systems North and South in 1864.
The Union converted part of Camp Rathbun in Elmira, New York, into a prison in the summer of 1864, and it began operating as a POW camp on July 6. Elmira soon held far more prisoners than its intended capacity, and poor sanitation and harsh winter conditions contributed to high death rates.
By mid-1864, Andersonville’s population swelled dramatically, outpacing food, shelter, and medical capacity. The exchange collapse meant prisoners stayed longer, and the camp’s overcrowding and disease became a major political and humanitarian issue as reports reached the North.
Grant wrote that exchanging prisoners would quickly return Confederate soldiers to the fight, arguing it was “hard” on Union prisoners but protected Union armies in the field. The letter became one of the most-cited documents in later debates over whether military strategy outweighed prisoner suffering.
After major Confederate surrenders in spring 1865, prisoner systems rapidly shifted from confinement to parole and return home. Overcrowded transportation and weak infrastructure created new risks for released prisoners, even after they left the camps.
A steamboat carrying large numbers of recently released Union prisoners—many from Southern prison camps—exploded on the Mississippi River. The catastrophe showed how the POW crisis had lasting effects even after release, turning a repatriation trip into a mass-casualty event.
Elmira continued processing Confederate prisoners after the war, including final arrivals and releases as the Union wound down its prison system. The camp’s wartime legacy—high mortality, overcrowding, and debates over responsibility—remained part of how Americans compared Union and Confederate prison policies.
Henry Wirz, the commandant most associated with Andersonville, was tried by a military commission and executed in Washington, D.C. His hanging became a major turning point in how the U.S. discussed responsibility for wartime prison conditions, with later arguments over scapegoating versus criminal accountability.
Civil War Prisons and POW Exchanges, including Andersonville and Elmira (1861–1865)