Actually, Paula, I would not list Abolitionists under either the Civil War nor under Black History, because abolitionists were active in the service of all kinds of slaves (indian slave most notably) and well before the Civl War as well as outside of the USA. I think professor "Box" Brown certainly belongs in the Slavery category.
But what I think would be helpful would be a sub-cat. of Civil War to cover civilians who served, as nurses, spies, workers in the Contraband Camps, and non-military leaders 'requisitioned' if you will, by the military (such as James Ward Porter).
These are people who served in the Civil War, but not as soldiers.
Shira