Photography played an important role during the Civil War capturing the horror of battle and the tediousness of camp life. Famous photographers like Mathew Brady managed to take thousands of photographs despite the limitations of 19th century technology. The "wet plate" process required long exposures and immediate developing. That is why there are very few photographs of actual battles.
Today's reenactors use historic images like those preserved at the
Library of Congress or the National Archives to research authenticity and develop better impressions.