As veteran readers know, I'm something of a Civil War student (yeah, we know...groan...) and, further, I've studied the Gettysburg campaign rather closely.
However, I was completely unaware of this, which is a gut-punch:
Race and Retaliation: The Capture of African Americans During the Gettysburg Campaign.
As it turns out, during the Army of Northern Virginia's last march north of the Mason-Dixon Line, there was a policy of reversing the Emancipation Proclamation, with blacks being captured and sent south for enslavement. It is beyond dispute that General James Longstreet was aware of it.
It is not pleasant reading. But it must be read. Hat-tip to the Dead Confederates blog for this find.