Petersburg, Virginia. Mortar Dictator. Photographed by David Knox, October 1864. Wikimedia Commons.Siege of Yorktown, Virginia: Confederate fortifications. Six men at sand-bagged cannon emplacement in right background. Unknown photographer, unknown date. Library of Congress.Federal Prisoners Captured at Battle of Bull Run, Castle Pinckney, Charleston, South Carolina, August 1861. Photograph shows Confederate soldiers above watching Union prisoners below in the yard. Unknown Photographer. Library of Congress.Confederate fortifications at Gloucester Point, Virginia, opposite Yorktown. Two men with cannon in foreground; ships on water in background. Unknown photographer, unknown date. Library of Congress.Bombproof Huts in the Front Line Before Petersburg, Virginia. August 10, 1864. Photographed by Timothy H. O’Sullivan. Library of Congress.Unburied Dead at the Battlefield of Gaines’ Mill, Virginia. Vicinity Cold Harbor. Photographed by John Reekie between 1861 and 1865. Library of Congress.Fort Burnham, Va., vicinity. Camp of the 5th Pennsylvania Cavalry near the battlefield of Oct. 29, 1864. Unknown photographer, between 1860-1865. Library of Congress.Old Frame House on Fair Oaks Battlefield, Pierced by Hundreds of Bullets, and Used as a Hospital by Hooker’s Division. Photographed by James F. Gibson, June 1862. Library of Congress.Confederate Prisoners Waiting for Transportation, Belle Plain, Virginia. Photographed by Mathew Brady, ca. 1860-1865. National Archives and Records Administration. Wikimedia Commons.Infantry regiment in camp. Probably 96th Pennsylvania Infantry at Camp Northumberland near Washington, DC, ca. 1861. Photographed by Mathew Brady. Wikimedia Commons.Civil War photograph of Ft. Stevens, Washington, D.C. Officers and men of Company F, 3rd Massachusetts Heavy Artillery, in Fort Stevens. Photographed by William Morris Smith, August 1865. http://www.nps.gov/cwdw/steven2.htm. Wikimedia Commons.District of Columbia. Detachment of Company K, 3d Massachusetts Heavy Artillery, by guns of Fort Stevens. Photographed by William Morris Smith, August 1865. Library of Congress. Wikimedia Commons.Confederate fortifications around Atlanta, Georgia, in 1864. The wagon and portable darkroom of photographer George N. Barnard is visible in the photograph. Photographed by George N. Barnard, 1864. Wikimedia Commons.Confederate Fortifications Around Atlanta, Georgia. Photographed by George N. Barnard, 1864. Library of Congress.A Bombproof Hut in front of Atlanta, Georgia. Photographed by George N. Barnard, 1864. Library of Congress.The ruins of Mills House and nearby buildings, Charleston, South Carolina, at end of American Civil War. A shell-damaged carriage and the remains of a brick chimney are in the foreground. Unknown photographer, 1865. http://www.archives.gov/research/american-cities/. Wikimedia Commons.United States Army Soldiers in Formation, Baton Rouge, Louisiana. Photographed by Andrew David Lytle, 1863. Wikipedia Commons.Black Soldiers of the Native Guard Regiments of the Union Army at Port Hudson, Louisiana, 1862-1864. This squad is in the “Parade Rest” position. Unknown photographer. National Archives and Records Administration. Wikimedia Commons.Commissioned officers of 19th Iowa Infantry after their exchange as prisoners of war, New Orleans, July 1865. Unknown Photographer. Library of Congress.Colonels Orlando M. Poe & Orville E. Babcock at Fort Sanders, Knoxville, Tennessee. Photographed by George N. Barnard between 1861 and 1865. Library of Congress.