The present study is a socio-political and military history of the development, use and demise of Old Capitol Prison. Built to serve the legislative arm of the Republic, Old Capitol stood at the corner of First and A Streets. From the time the federal government assumed control of the building in 1861, it served as a prison for several classes of persons before its ultimate demise in 1865. Federal officials were overwhelmingly unprepared for the task of prisoner control. At no point before the outbreak of hostilities had any official advocated the maintenance of a permanent military prison system. A severe lack of planning and foresight created a veritable void, casting vast numbers of prisoners into hastily assembled prisons. In the District of Columbia, the building called "the Old Capitol" provided a warehouse for such prisoners. Prisoners confined in Old Capitol were of several categories. Confederate prisoners-of-war found residence there. As Lincoln's armies occupied Confederate territories, civilians of "secesh" political leanings were taken into custody. Persons of Southern political leaning in the border states found their way into Old Capitol. They were joined later by persons of similar persuasion from states both north and west. Slaves and white refugees flowing out of the South were also placed in the custody of the federal guard. Northern military men accused of alleged crimes, disloyalty, dissertion, etc., were guests of their own system. Old Capitol served as host for a vast variety of guests. This study attempts to tell their story. / Master of Arts