I think that the previous post was quite comprehensive. I might also suggest that one of the critical elements in Black literary expression in the time period was dealing with the dualistic ends of slavery in terms of both its presence and absence. Black writers of the time period were wrestling with its presence leading into the Civil War. After the war's conclusion, literary thinkers, and thinkers in general, were doing battle with what it means to be Black in America coming out of the Civil War. This led to divergence in thought and understanding for it was a new frontier being crossed by all people of color in a new nation, forged by misunderstanding the issue of race and ethnicity but immersed in economic progress where such issues were for the most part deferred.
In the 19th century, one of the defining events is the Civil War (1861-65). Around this time, a Women's Liberation Movement began, correlating with the Abolitionists. Elizabeth Blackwell was the first female medical student (1848 I think). So these two movements were parallel and encouraged by each other. This is comparable to the Civil Rights Movement a century later in the 1960s, although the 1960s took it to a whole new level - such is the nature, hopefully, of progress. Given that background at least during that time, much of African-American literature in the 19th century was autobiographical/historical or the novel, the prime example being Harriet Beecher Stowe's Uncle Tom's Cabin. But I think the most significant genre was the slave narrative. I think one of the most important works was Frederick Douglass' Narative of the Life of Frederick Douglass, an American Slave, Written by Himself (1845). It gave a lot of authenticity to the Abolition movement because it was so insightful and profound and because it was written by an African-American. (Lots of abolitionist literature was penned by whites). Perhaps even more importantly, Douglass stressed the need for education and literacy. One of his famous quotes, and I'm paraphrasing here, was something along these lines: "The more I read, the more I desire freedom."
This is not the one I'm thinking of, but it fits as well:
"To educate a man is to unfit him to be a slave."