AUDIE CORNISH, HOST:
From NPR News, this is ALL THINGS CONSIDERED. I'm Audie Cornish. We end this hour marking the bloodiest single day in American history. 150 years ago, Union and Confederate troops clashed at the small Maryland town of Sharpsburg, next to Antietam Creek. By nightfall, some 23,000 men would be dead, wounded or missing. NPR's Tom Bowman explains how this one day would change the course of the Civil War.
(SOUNDBITE OF LEAVES CRACKLING)
TOM BOWMAN, BYLINE: It could be any other cornfield in late summer. It's lush, the stalks are over five feet and the ears are plump, just like they were a century and a half ago, when Union troops from New York and Pennsylvania emerged from this green cover and were shot by Southern troops from Georgia.
KEITH SNYDER: In and around the cornfield in about a half-mile radius from where we stand, 10,000 soldiers are killed and wounded in four hours.
BOWMAN: Keith Snyder is a ranger with the National Park Service.
SNYDER: There is no other spot like this in American military history.
BOWMAN: Those Georgian troops were part of General Robert E. Lee's invasion of the north. Lee had been victorious against Union troops in Virginia during the first year of the war. Now he was convinced he could take the fight to the Union's backyard.
STEPHEN SEARS: Lee had always felt that he had to make an aggressive war, that the South could not tolerate a long, drawn out war, and so this was the opportunity.
BOWMAN: Stephen Sears wrote a book about Antietam called "Landscape Turned Red." He says Lee's focus was not just Northern soldiers but Northern politicians, who were tiring of the fighting and getting ready for elections just two months away.
SEARS: He had his eye on the Northern elections, mid-term elections hoping that there might be a peace party that he could encourage by having his army in Maryland. And so he really wanted to win a showdown battle on Northern territory if he could.
BOWMAN: President Lincoln also wanted a showdown battle. He urged his commander, General George McClellan to destroy Lee's army. Lincoln sent McClellan a cable with this instruction: Please do not let him get off without being hurt. Lee's army was hurt by day's end, but so too was McClellan's. The 23,000 casualties were split almost evenly between the two sides.
SEARS: Antietam, at least for me, is the most tragic day of the war.
BOWMAN: Again, author Stephen Sears who says McClellan had the edge because he greatly outnumbered Lee.
SEARS: All of the odds seemed to be in favor of this being a great, if not a war-ending, at least a crucial battle. But it ended up more or less a stalemate and we had to keep doing it again and again for two more years.
BOWMAN: But this partial victory allowed Lincoln to reach a political decision. Five days after Antietam, the president issued the Emancipation Proclamation and told his cabinet, God has decided this question in favor of the slaves. Keith Snyder, the park ranger at Antietam, says Lincoln's decision changed the purpose of the war.
SNYDER: No longer is this just about reunification. It's about freedom for four million Americans.
BOWMAN: The battle lasted just one day, and would take a week to bury the dead. And for the first time, a photographer, Alexander Gardner, was there to take pictures of the corpses - at the Cornfield and Bloody Lane and Burnside Bridge. The next month, Gardner's boss, Matthew Brady, arranged the pictures at his Broadway studio. He called the exhibit simply, The Dead of Antietam. A New York Times reporter who was there wrote this: Mr. Brady has done something to bring home to us the terrible reality and earnestness of war. If he has not brought bodies and laid them in our dooryards and along streets, he has done something very like it. Tom Bowman, NPR News, Washington. Transcript provided by NPR, Copyright NPR.