National Archives and Records Administration (NARA)

AmericanCivilWar.com
Civil War Photographs

CivilWarPhotos.net
Civil War Photographs

GeneralsAndBrevets.com
Generals of the Civil War

National Archives
Emancipation Proclamation

National Archives
Pictures of the Civil War

National Archives
Slave Trade Records that pertain to American Slavery and the International Slave Trade

Smithsonian Institute
Mathew Brady National Portrait Gallery

USAcivilwar.com
Civil War Photographs