Civil War Studies at the Smithsonian Associates
http://civilwarstudies.org/

Kathleen W. Dorman, “Interruptions and Embarrassments’: The Smithsonian Institution during the Civil War” [The Joseph Henry Papers Project]
http://www.si.edu/archives/ihd/jhp/Civilwar.htm

Mary Henry: Eyewitness to the Civil War in the City of Washington
http://www.si.edu/archives/documents/mary.htm

Mathew Brady's Portraits
http://www.npg.si.edu/exh/brady/index.htm

West Point in the Making of America
http://americanhistory.si.edu/westpoint/

Winslow Homer to George G. Biggs, February 19, 1876, regarding sharpshooters
http://archivesofamericanart.si.edu/exhibits/illusltr/homer.htm