At the war's start, a parole system operated, under which captives agreed not to fight until exchanged. They were held in camps run by their army, paid, but not allowed to perform any military duties. The system of exchanges collapsed in 1863 when the Confederacy refused to exchange black prisoners. After that, about 56,000 of the 409,000 POWs died in prisons, accounting for 10 percent of the conflict's fatalities.