The soldiers in the photographs are in uniform, often holding a weapon. Sometimes two. In rare instances — which makes it a valuable collector’s item — three different weapons were captured in the frame: a pistol, a knife and a musket. But a universal element of Civil War portrait photography is the soldiers’ youthfulness and the look of determination and resolve in their eyes, according to Bob Zeller, president of the Center for Civil War Photography and author of “The Blue and Gray in Black and White: A History of Civil War Photography.”

Washington Post photographer Matthew McClain spent the week in Gettysburg, Pa., documenting the events marking the 150th anniversary of the deadly battle there. He photographed reenactors in the style of portrait photography from the Civil War era, a style shaped by the solemnity of the occasion of being photographed and the limits of technology.

Abraham Lincoln was likely the most-photographed person of the period, and there are only about 150 documented photographs of him.

So, for the young soldiers who had their portraits taken by the camp photographers who traveled with the Army or who paid the equivalent of a few dollars at a portrait studio, it was a very rare occurrence to be in front of a photographer’s lens. The portraits reflect that.

Most soldiers were photographed using tintypes, which, Zeller noted, required an exposure of anywhere from three seconds to, on a really cloudy day, 20 seconds.

“You knew you had to sit still for a good photograph,” he said. “They had neck braces they would place you into. This would contribute to the formality and lack of smiling. It tended to make people a little nervous.”

The popularity of photography during the Civil War — the first American conflict in which photographs were available to the masses — makes this momentous event in American history accessible to us today, in Zeller’s view.

“We can look in these guys faces and really see them,” he said.

photos by Matthew McClain