I have studied the Champion Hill battle, and as per Gen. Cumming's OR...

"The brigade line was established on a succession of slight ridges overlooking a clear field. Strong parties of skirmishers were at once thrown out beyond this field, with directions to penetrate the woods on the other side and engage and hold in check those of the enemy. This they did under the efficient management of Lieutenant-Colonel [J. F. B.J Jackson (Thirty-ninth Georgia) commanding.

Then Gen Cumming states latter:

"Having sent forward an officer of my staff to notify the officer commanding the skirmishers of the change of direction of the line, and to direct him to make their movements to correspond, I at once proceeded from the center to the extreme left of my brigade, to superintend the change. The directions above referred to were communicated to the officers in command of the skirmishers, but owing to the distance of this line in advance, the inability in a wooded country of determining the point at which the change of direction should be made, and especially to the fact that they were unable to keep up communication with the skirmishers of Lee's brigade, they were unable to follow up the movement, and later in the day were forced, after a gallant contest, in which they suffered severely, to retire toward the right.

What I'm most curious about is WHEN those Skirmishers were actually forced back in the battle...was it before Gen. Buford's Brigade counter attacked, or at the same time that Buford's Brigade was forced to make a fighting withdrawal?

I have the excellent book by Timothy B. Smith: Champion Hill Decisive Battle For Vicksburg.
I just can't find a definitive point the 39th GA skirmishers were forced to retreat.
Respectfully:

Kevin Dally