One hundred and fifty years ago, Alexander Gardner must have breathed a heavy sigh as he crossed a field of misery and woe in western Maryland, pulling along his mule and a rattling wagon that contained his darkroom, filled with glass plates and volatile chemicals.

More than 23,000 Union and Confederate soldiers were killed or wounded at Antietamthe bloodiest day in American history. Because of the scale of destruction, when Gardner arrived two days later many soldiers still lay where they were cut down. This being the early days of the photographic process, Gardner and his assistant, James Gibson, had to choose their frames wisely. Supplies were limited, and the work of burying the dead had already begun.

Of the 70 images Gardner captured over the following days, I am fascinated with this one most. It was part of a series of “death studies” that Gardner made. Many of these studies, including this image, were stereographs; early 3-D images created with a system of dual lenses capturing two simultaneous photographs. Before this point in the 18-month-old conflict, no one had depicted the horror of war in such an unflinching manner, especially not in 3-D. (Only the left-hand portion of this stereograph has been reproduced here.)

Initially, this photograph seems to depict a man sleeping serenely in a field, until you read the caption. Originally detailed on the negative sleeve, it offers a simple, stirring narrative: Where was he going, dragging himself along? Whose face filled his eyes when they closed, trying to shut out the horror of a day that still has us shaking our heads in disbelief? Look closely; what do you see?

At first I couldn’t make out the shape of the little ravine described herein, but now I see how his form gently rests in the contours of its path, almost cradling and comforting him. This is an incredibly personal image, capable of evoking an easy sense of peace at first, only to reveal a man desperately crawling to some place, any place, out of sheer hell.

At this point no one had ever photographed dead soldiers before they were buried. The photographic process was still quite young and cumbersome. Newspapers could not yet reproduce these images, relying instead on rough woodcuts of their likeness.

People were shocked and horrified when these images were first put on display in New York a few months later. The New York Times stated that Gardner was able to “bring home to us the terrible reality and earnestness of war. If he has not brought the bodies and laid them in our door-yards and along streets, he has done something very like it.”

The American Civil War was the first major conflict in human history well documented in photographs. Now, war photographers still slog through violent conflicts around the globe, attempting to document the total human cost of war. May their work not be in vain.

This is the first installment in a series of essays on the photographic process and the art of arresting images called Affixed. D.L. Anderson is an award-winning staff photographer for Indy Week.