In Kent Masterson Brown's "Retreat from Getysburg," he states that Imboden, had brought the train of wounded to Williamsport from Gettysburg, escorted by his 600 second-rate troopers. When a couple of Buford's scouts were captured, Imboden realized he was in danger, and set his men and noncombatants to work improving the fortifications, dating from the year before. He also sent runners through the wounded camp, asking if any could take a musket, and got about 200 walking wounded. At this point, something like 1500 teamsters, nearly all slaves, volunteered. So Buford found the fortified camp defended by an approximately equal force. Since they were in static dug-in positions, no extensive training was needed, and the troopers provided a core of seasoning, enough to hold off cavalry.
Is this an example of armed slaves fighting for the Confederacy?