16 1/8 x 11 1/4 in. albumen photograph on 19 3/8 x 15 1/4 in. mount (toned, a few small spots to lower right; dampstaining to upper mount edge).

Four uniformed soldiers lean against Fort Warren's guardhouse to the left while a fifth soldier stands at attention near a sentry box. A civilian figure leans a hand on the wall.

Completed shortly before the war, Fort Warren is located on Georges Island in Boston Harbor and served as a prison for both prisoners of war as well as Confederate political prisoners. Regarded highly for its relatively compassionate treatment of prisoners, only 13 died while imprisoned. Notable detainees include Confederate Vice President Alexander H. Stephens; James M. Mason and John Slidell, the diplomats involved in the Trent affair, Richard S. Ewell, Adam "Stovepipe" Johnson, and Simon Bolivar Buckner, Sr.

It was also here that John Brown's Body was first performed at a flag-raising on 12 May 1861. It spread throughout the Army of the Potomac by men from the 12th Massachusetts Infantry ("Webster's Regiment").