One hundred fifty years ago the nation was in the midst of a war against itself. Memorial Day provides a particularly suitable occasion to consider the imagery of the Civil War and its extensive death toll, as depicted in the photography of that era.

Photography and the American Civil War is an encyclopedic exhibit of images created during this wartime period from 1861 to 1865. The exhibit, at the Metropolitan Museum of Art, documents the camera’s extensive role in capturing the Civil War, just twenty years after the invention of photography. It is a sampling of the hundreds of thousands of images produced and collected during this period from keepsakes to historical records to medical documentation.

The exhibit opens behind tent-like decor with a portrait of Abraham Lincoln taken on May 20, 1860, his first portrait after receiving the Republican presidential nomination just two days prior. The future president – 51 at this point – appears youthful without his signature beard or stovepipe hat.

Next is a campaign button for Lincoln from the same year. The button is a thin sheet of iron holding a photographic image of the candidate surrounded by a red, white, and blue ribbon. The image was produced using a positive process, similar to daguerreotype, known as “tintype,” which was light and cheap to manufacture at the time.

Because of the long exposure times required for early photographs, it was difficult to take action shots of the frontlines during battle. Timothy O’Sullivan took the first such shot of the war, a long exposure of a Pennsylvania artillery battery in Petersburg, VA, in 1864. However, this may have been an exercise and not real combat. The willowy figures silhouetted against the battlefield give an eerie feel to the picture. It is a sharp contrast with an earlier picture featured in the show by Matthew Brady, depicting a group of Union infantrymen drilling near Washington in 1862. The scene is captured in almost crisp detail, with soldiers in a line, bayonets raised.

On the Abolitionist front, there is an iconic portrait of Sojourner Truth, by an unknown photographer, casually pausing to look up from her knitting. The title of the picture is “I Sell the Shadow to Support the Substance,” as the Abolitionist sold her portrait, her “shadow,” to support her causes of freeing the slaves and women’s suffrage. A related image is Andrew Joseph Russell’s “Slave Pen,” depicting a storefront for a slave trading operation where 300 to 400 slaves were kept at a time.

Alexander Gardner began publishing “Gardner’s Photographic Sketchbook of the War” in 1866, the first photographic anthology to be published. All but two of the photographs were taken by Timothy O’Sullivan, notably, “A Harvest of Death, Gettysburg,” from 1863, documenting the massive death toll on the battlefield. Other “incidents of war” include “Field Where General Reynolds Fell” showing dead bodies splayed across the field at that Pennsylvania battleground.

The huge number of casualties during the war prompted another interesting use of photography during this time, for medical documentation. Dr. Reed Brockway Bontecou was the first physician to employ photography in professional use, such as the image of amputee Private Samuel Shoop, a Pennsylvania Infantryman, in 1865. The pictures of varying medical conditions were for instructional use, such as “Amputation at Field Hospital,” by an unknown artist, showing a surgeon about to amputate an arm while an attendant sedates the patient with ether.

There are numerous keepsake photos throughout the exhibit with images in lockets lined with velvet and even holding locks of the beloved one’s hair.

The exhibit closes with the death of Lincoln, and a collage of eight photos in memory of the slain president. These include a broadside advertising the reward for the capture of John Wilkes Booth at $50,000 and his two accomplices at $25,000 each, with photographs of them all. Just as the show opens with the campaign button for Lincoln, it closes with a mourning corsage of a very similar design with a round tintype picture and ribbon, a poignant tribute to the man who ended the war and slavery in his short tenure.

Photography and the American Civil War appears at the Metropolitan Museum until September 2. 1000 Fifth Avenue, New York, NY, (212) 535-7710, www.metmuseum.org.

Lisa Tannenbaum is an art historian and photographer. Her images can be seen at www.lisatannenbaumphotography.com.