The following links are websites that will be helpful in your research.
Civil War Related Websites from American Battlefield Trust
Frederick Douglass Papers at the Library of Congress
The Slave, Freedom, or Liberation Narrative
Literature from the American Civil War (Newberry Library)
"How the Civil War Transformed American Literature:" A Talk by Randall Fuller
Library of Congress Civil War in America exhibit
National Endowment for the Humanities Literature of the Civil War