What reasons might there be for inflating the role of blacks on both
sides of the conflict?

At the onset of the Civil War, free black men rushed to volunteer for service with the Union forces. Although African Americans had served in the army and navy during the American Revolution and in the War of 1812 (few, if any served in the Mexican War), they were not permitted to enlist because of a 1792 law that barred them from bearing arms in the U.S. Army. President Abraham Lincoln also feared that accepting black men into the military

Explanation:

can you show the map , i'll be able to update my answer