Virginia Lomax, b. 1831: The Old Capitol and Its Inmates - 1867 first-person account of life in the Old Capitol Prison and Carrol Prison, which housed prisoners during the Civil War. Full text (226 pages). A volume in Documenting the American South, a series of electronic text reprints. - http://docsouth.unc.edu/fpn/lomax/menu.html
District of Columbia Emancipation Day Foundation - Formed to preserve the history of slave emancipation in the District of Columbia on April 16, 1862. Includes a brief history. - http://www.dcemancipation.org/
Battle of Fort Stevens - Short account of the battle in which General Jubal Early's Confederate forces were repulsed at Fort Stevens, just north of Washington, in July 1864. - http://www.americancivilwar.com/statepic/dc/dc001.html
Mr. Lincoln's White House - An account of Lincoln and of the White House and Washington during his Presidency. - http://www.mrlincolnswhitehouse.org/
The Diary of Horatio Nelson Taft, 1861-1865 - Documents daily life in Washington, D.C., through the eyes of Taft, an examiner for the U.S. Patent Office, and includes an account of Lincoln's assassination. Site has page images of the three manuscript volumes, transcriptions, and a biography of Taft. - http://memory.loc.gov/ammem/tafthtml/tafthome.html
Civil War Defenses - Describes the system of forts defending the city during the Civil War. Official National Park Service site. - http://www.nps.gov/rocr/ftcircle/
Rose O'Neal Greenhow Papers - Greenhow, a leader in Washington society, was also one of the most celebrated Confederate spies in the Civil War. Site has letters and news clippings from the collections of Duke University, plus historical background information. - http://scriptorium.lib.duke.edu/greenhow/