These images were taken by small-town photographers and traveling camp photographers, which combined topped 5,000 by the time war broke out in 1861, Zeller said. More than a million such images were produced during the war.
Officers had their photos taken as well and often passed them out to the men as a morale booster. New ways to reproduce photos gave birth to cards. The Library of Congress has produced an exhibit of soldier's portraits April 12 called "The Last Full Measure," based on a private collection.
The second kind of photo was the carte de visite. The carte de visite, or cdv, was also primarily a portrait photograph, except it was made with a glass, wet-plate negative, which meant unlimited copies could be created. Prints were made on albumen paper, according to the center. These portraits of generals, statesmen, actors and other celebrities were mass produced and given out like trading cards.
Some of the Civil War photographers, including Brady, have been criticized in recent years because it appears they moved corpses to create more graphic images. But Zeller said it wasn't a common occurrence. Given that each photographer need an entire wagon worth of equipment and chemicals, he said, these post-battle photographers faced their own set of challenges.