These McClellan designating flags were dropped in 1863-1864 and repalced with a simpler system for brigades, divisions and corps. The late Howard Madaus wrote of both in articles that can be found in older issues of Military Collector and Historian which is a publication of the Company of Military Historians of which I am a member.

I would also advise you go up to Carlisle, PA before you deploy as they are Civil War research Valhalla in my book. They carry the journal mentioned above.

Greg Biggs