At the beginning of the American Civil War prisoners of war were paroled or exchanged but by April 1864 prisoners from both sides were being held in camps for the duration of hostilities. Some of the camps on both sides became notorious for the appalling conditions under which the prisoners were held. One of the worst was Fort Sumter in Andersonville, Georgia where 45,000 Union soldiers were held and around 900 died each month from malnutrition or disease. There were similar camps set up by the Union where treatment of prisoners was equally bad, e.g. Elmira and Fort Delaware. The North also established camps for civilian populations considered to be hostile to the Union. These were called ‘posts’.
In 1895 the Spanish, when seeking to suppress a rebellion in Cuba, established ‘reconcentrados’, camps for civilian populations to separate them from rebel forces who were fighting a guerrilla campaign. Over 300,000 were located in these camps where thousands died from starvation and disease.