Sliven was a prisoner-of-war camp established in Sliven in 1915 with the intent of housing Serbian troops captured during the course of World War I. Over time Greek and Serbian civilians joined their ranks reaching 19,000 at its peak. From 1916 until its dissolution in 1918 then camp served as a punitive institution. Internees suffered from the lack of proper housing conditions, typhus, malnutrition and ill treatment from their guards. This led to the deaths of over 6,000 prisoners.