People.
It's clearly going to be a dlc that adds in Robert, William and Tad Licoln, who traveled back in time to stop the Confederacy from getting support from England in a alternate reality where the European powers intervened in the US Civil War. Hence, the "Sons of Abraham"
It's so obvious.
Clearly, this will also incorporate the Vampiric Confederacy as well, and Abe Lincoln will have the trait "Slayer".