"A Burial Party, Cold Harbor, Virginia," photographed by John Reekie in 1865, depicts African American soldiers collecting corpses from the site of a massive battle which took place in May-June 1864.
The recently-invented medium of photography allowed Americans for the first time to see images of war as it really looked ... the first time true likenesses of the people who lived and died in the Civil War remained as a record, profoundly shaping our understanding of the bloodiest conflict in U.S. history.
Iconic images from that period are collected in a new exhibit by the Metropolitan Museum in New York City, "Photography and the American Civil War."
By CBSNews.com senior producer David Morgan
Photographer Roger Fenton (1819-1869) took this image of his photographic van (showing his assistant Marcus Sparling) during the Crimean War in 1855.
Fenton's pictures were an early attempt to document war with a camera, but his images were mostly of the landscapes and participants of the conflict.
Harper's Weekly (published 1857-1912) was the leading pictorial publication of its day, reproducing woodcut illustrations. As the Civil War progressed, line art illustrations based on photography from the battlefield helped make the paper one of the definitive documents of the war. (It would be at least another two decades before half-tone printing allowed for the direct reproduction of photographs in newspapers.)
Left: An illustration depicting Confederate forces bombarding Fort Sumter in South Carolina, launching four years of bloody civil war in America.
Within hours of the fall of Fort Sumter, on April 14, 1861, damage from the Confederate bombardment had been photographed.
Left: A stereograph shows a Confederate flag raised above Fort Sumter.
A lantern slide (meant for projection in an auditorium) by photographer James F. Gibson, shows Battery No. 4 near Yorktown mounting ten 13-inch mortars, May 1862.
This image by George Bernard, who was a photographer for Gen. Sherman, shows the ruins of Rolling Mill and an ordnance train on the Georgia Central Railroad, destroyed by Confederate troops under General John B. Hood, during their evacuation of Atlanta in 1864.
Mathew Brady (1822-1896) was the leading American photographer of his day. He began photographing the Civil War during the First Battle of Bull Run in 1861, at which he narrowly avoided capture. At left Brady is pictured shortly after having returned from the site of the Virginia battle.
Mathew Brady's mobile photo outfit is seen in a field in Petersburg, Va., c. 1864.
There were field photography studios in tents with skylights. Early on, photo supplies became almost impossible to get in the South, so photographers followed the Union armies, edging closer and closer to the battlefield.
Subjects had to sit or stand absolutely still for as long as eight seconds then. Pictures were taken on glass plates, and printed outside in the sun.
Left: Soldiers pictured at Arlington Heights.
Photographs were already cheap -- 50 to 75 cents, with a fancy folding case, or five to ten cents printed as glorified postcards.
A tintype of a woman holding a pair of quarter-plate soldier portraits -- images of men who might never return home from battle.
Tintype portrait of Lt. William O. Fontaine, Company I, Twentieth Texas Infantry, pictured 1862-1865.
From left: Benjamin, George, James and John Pattillo, of Henry County, Ga., are pictured holding a Bowie or side knife. They had joined Company K of the 22nd Regiment of the Georgia Volunteer Infantry.
Benjamin Pattillo (who is also holding a hand grenade) died from a bullet wound suffered at the Second Battle of Bull Run. James was shot in the foot in the Battle of Second Deep Bottom, leading to the amputation of a toe. John was wounded at the Seven Days' battles near Richmond in 1862.
John Lincoln Clem ran away from home at age nine to join the Union forces in 1861. He tagged along with the 22nd Michigan, serving as their drummer boy, and received the title of Sergeant after shooting a Confederate colonel who demanded he surrender at the Battle of Chickamauga in September 1863.
By the time Clem retired from the Army in 1915 he had attained the rank of Brigadier General.
An unknown photographer captured this portrait of Confederate Private James Malcolm Hart of Crenshaw's Virginia Battery, wearing a shiny, oilcloth poncho with rubberized head and neck gear.
Timothy H. O'Sullivan's photograph, titled, "Field Where General Reynolds Fell, Gettysburg," shows the remains of Union soldiers -- bloated, and looted of possessions and boots.
As powerful as these images of war dead are, they also show the limitations of Civil War-era photography: You could take pictures before the battle, and after the battle, but not during the battle, because of the long exposures required.
"The camera really couldn't capture that movement," said Jeff Rosenheim, head of the Metropolitan Museum of Art's photography department.
Timothy O'Sullivan's photograph of the Pennsylvania Light Artillery, Battery B, in Petersburg, Va., 1864.
The Scottish-born photographer Alexander Gardner (1821-1882) was appointed a staff photographer under General George B. McClellan. He became famous for his Civil War-era images, including the aftermath of the Battle of Antietam.
An image of a Confederate soldier by Alexander Gardner, taken on the Battlefield at Antietam, near Sharpsburg, Md., in September 1862.
Antietam was the bloodiest battle of our bloodiest war, with 23,000 dead and wounded.
At left: One of two images by Alexander Gardner of a fallen Confederate soldier, this one titled, "Sharpshooter's Last Sleep."
At left: "Home of a Rebel Sharpshooter," also by Alexander Gardner, shows the same Confederate sharpshooter.
How did that happen? "Some Civil War historians suggest that the photographer, Gardner, and his assistant, O'Sullivan, found [the corpse] in the open field and moved it to this little nesty area," Rosenheim told CBS News' Martha Teichner. "Other people believe that the body was found and removed by a burial detail to [the other] location."
Alexander Gardner photographed the charred remains of the Gallego Flour Mills, on the James River in Richmond, Va., resulting from a massive fire that decimated large swaths of the city's commercial district in April 1865.
A surgeon for the Union Army, Dr. Reed Brockway used photography to document the wounds received by soldiers.
Left: Sgt. Brazer Wilsey, Company D of the Fourth New York Volunteers.
Dr. Bontecou's pictures of war wounds and amputees were later used to teach medical students.
Alfred A. Stratton lost both arms while serving in Company G of the 147th New York Volunteers.
Stratton was one of many Civil War veterans who sold pictures of their amputations in order to raise donations.
A. J. Riddle (1828-1897) photographed this view of the stockade at the Confederates' Andersonville Prison in Georgia, August 17, 1864. At the time the camp held 33,000 Union prisoners of war.
Frances Clayton followed her husband into battle, disguising herself as a man and fighting alongside him.
"Contraband Aboard the USS Vermont," an 1861 photograph by Henry P. Moore (1833-1911).
Before the Emancipation Proclamation, escaped slaves were classified as "contraband" by the Union Army, so as to not return such "property" to plantation owners. Instead, many former slaves became conscripts for the Union Army, such as this group pictured aboard a ship in the Union's South Atlantic Blockading Squadron, in Port Royal, S.C.
Abolitionists quickly figured out that photographic evidence of the treatment of blacks was a powerful argument for the anti-slavery cause.
This Mathew Brady photograph, "The Scourged Back," taken in 1863 in Baton Rogue, La., shows a runaway slave named Gordon who was being treated by Union Army doctors, before joining a Union Colored regiment. The image, showing the scars from his master's whip, found its way into the 2012 film, "Lincoln."
Myron Kimball's December 1863 group portrait of emancipated slaves.
The figure on the far left, Wilson Chinn, was sold at age 21 to the owner of a Louisiana sugar plantation, who branded many of his slaves with a hot iron. The initials of the plantation owner, Volsey B. Marmillion, were visible on Chinn's forehead (though the negative was slightly retouched to make the brand more visible in prints).
Andrew Joseph Russell (1830-1902) photographed emancipated slaves working as laborers at Quartermaster's Wharf, Alexandria, Va.
Sgt. Alex Rogers carries the battle flag of the 83rd Pennsylvania Volunteers, c. 1863.
When President Lincoln was assassinated in April 1865, photography helped catch his killers, with the first broadsheet wanted poster in American history illustrated with albumen silver print photographs.
"Photography was everywhere," said Jeff Rosenheim. "It had really saturated American society, and they just needed to actually go to the boarding house, to the family homes, to the friends of the likely conspirators to find pictures of them."
The image used of John Wilkes Booth was a publicity shot taken of the actor.
Four of Booth's co-conspirators were hanged. Pictures taken at the gallows were printed and sold.
"Collected for Burial" shows corpses at the site of the Battle of Antietam, from the Mathew Brady Studio.
"I think that we are as a nation only as good as our memory," said the Met's Rosenheim, "and the facts of these photographs, their tradition, gives us something that we cannot forget."