He became a leader in the abolitionist movement, which sought to end the practice of slavery, before and during the Civil War. Frederick Douglass: Later Life and Deathįrederick Douglass was a formerly enslaved man who became a prominent activist, author and public speaker.Frederick Douglass During the Civil War.Frederick Douglass in Ireland and Great Britain.'Narrative of the Life of Frederick Douglass'.Frederick Douglass Escapes from Slavery.