Black Confederates at the Siege of Petersburg?

A regimental history of the 36th Wisconsin by James M. Aubery, published in 1900, contains his observation of so-called “Black Confederates”, and whether or not they were soldiers.  I think Aubery’s statement¹ speaks for itself on the matter, emphasis mine.

The following from General Longstreet regarding Hatcher’s Run explains itself and shows that the slaves were quite a factor in the Confederate Army, although they were not in the ranks to fight, but were put on the works, saving the strength of the fighters. Our army had to build their own forts and breastworks. Also, the reader will note that General Longstreet anticipated a move before election, as did General Grant, by his “confidential” circular to the commanders of the corps:

Headquarters, October 29th, 1804. Gen. B. E. Lee,

Commanding Army of Northern Virginia: General: The operations of Thursday must have developed the feasibility of a grand attack upon either points on my left. In view of the damaging effects of the late operations upon the prospects of the present Yankee administration and the importance of some decided success before the approaching election, I am apprehensive of a formidable effort to break through my line at an early moment. If I am obliged to stretch out my line as much as I did on Thursday, a grand attack must go through it. I suggest, therefore, that all of the negro force we have and all that is at work around Richmond be put at work to build a line from the battery on the Charles City road to the point where the enemy last crossed White Oak Swamp. I think that I might hold such a line until I could get re-enforcements. The other crossings of the swamps can be held by cavalry for some time. * * * Most of this new line could be put up to-morrow if all the negroes were put to work at it. If they can be sent I should be advised, so as to make my line of skirmishers stronger in front of that part of the line. I am, etc.,

J. LONGSTREET,

Lieutenant-General.