Great re-enactment for you to catch Lew and thanks for sharing those photos.
While many of these battles have re-enactments every year, the really big ones (with hundreds or thousands of re-enactors) are on major anniversaries. This is the 150th of Cedar Creek. So what that means is (since there were few battles in the winter), you're going to see some re-enactments next spring and then the really big affairs that have thousands of re-enactors will be gone for a decade or more. So those of you who want to shoot stuff like this (especially with multiple units and several hundred or even several thousand re-enactors) you need to get out there this next spring.
Also, the annual Antietam Memorial Illumination will be Dec. 5th this year (Antietam National Battlefield, Sharpsburg, MD). It's the single bloodiest day in American history...23,000 candles (one for each casualty) are placed on the battlefield. It's a stunning sight. And the Antietam battlefield is one of the most pristine in the US--nothing like Gettysburg or Fredericksburg where commercial or residential sprawl has affected things. The battlefield is almost identical to what it looked like back then--the NPS even plants corn in the The Cornfield.