Not having the locations to detain or otherwise accommodate large numbers of captured troops early in the war, the U. S. and Confederate governments relied on the traditional European system of parole and exchange of prisoners of war. The French parole d’ honneur was a pledge or oath under which a prisoner of war (POW)was released with the understanding that he will not again bear arms until exchanged for an enemy captive of equal rank. Sometimes the parolees went home to await notice of their exchange; sometimes they waited near their commands until the paperwork was processed.
As the war continued, the system became increasingly complex and cumbersome. Also, the system became tremendously expensive as the number of parolees soared. The prospect of being sent home encouraged many men to be captured in battle or allow their capture through straggling. Detention camps established by the Federals angered parolees, as did attempts to use them as guards and other non combat and assignments.
This of course eliminated the opportunity of going home, but it was a serious violation of the law and was punishable through the military courts.
An odd arrangement occurred in July 1862 when Col. N. B. Forrest captured parts of three Federal regiments at Murfreesboro, Tennessee. Finding his command short of guards to escort the 900 prisoners, he picked a willing number from among them to drive the many wagons he captured. On arriving at McMinnville, he made good a promise to parole them with two days rations thrown in to start them to their northbound homes.
Federal authorities generally withheld parole and exchange from guerillas, bushwackers, and blockade runners, which resulted in retaliatory action by the Confederacy.
Finally admitting that the war was being prolonged by returning men to the ranks through parole and exchange-which by 1863 was the Confederate army’s principal means of maintaining troop strength, the Union high command severely restricted the program. Gen Grant on April 17, 1864 ordered that prisoner exchange cease altogether. From then on confining enemy troops to prison camps became the policy for the two belligerents. (Patricia L. Faust, Encyclopedia of the Civil War, 1986)