Jackson provided the Union Army with key secrets about the Confederacy.
He learned high-level details about Confederate battle plans and movements because Davis saw him as a "piece of furniture" -- not a human, according to Ken Dagler, author of "Black Dispatches," which explores espionage by America's slaves.
"Because of his role as a menial servant, he simply was ignored," Dagler said. "So Jefferson Davis would hold conversations with military and Confederate civilian officials in his presence."
In late 1861, Jackson fled across enemy lines and was immediately debriefed by Union soldiers. Dagler said Jackson provided information about supply routes and military strategy.
Jackson and other slaves' heroic efforts have been a forgotten legacy of the war -- lost amid the nation's racially charged past and the heaps of information about the war's historic battles. But historians over the last few decades have been taking an interest in the sacrifice of African Americans during those war years.
More of the story here.