09/17/2012 07:18 am ET Updated Nov 17, 2012

Antietam Tells The Story Of America's Bloodiest Day

SHARPSBURG, Maryland -- It would be hard to imagine a more aesthetically appealing battlefield than Antietam: 3,250 acres of neatly maintained fields and 19th-century farmhouses spread out over gently rolling hills, separated by zig-zag split-rail fences and tastefully accented throughout by nearly 100 sometimes ornate, sometimes simple marble and granite monuments and some 500 forever silent cannon. In today's increasingly harried world of tacky urban sprawl, pastoral Antietam -- 70 miles west of Baltimore and 70 miles northwest of Washington, DC -- exudes the kind of timeless serenity that urges passersby to stop and enjoy an old-fashioned picnic.

But what happened here on September 17, 1862, was anything but a picnic. It was instead the single bloodiest day ever in American history, with some 3,650 American soldiers losing their lives in just 12 hours. The overall total of 23,000 casualties (killed, wounded, captured, or missing) was more than in the entire Revolutionary War, War of 1812, and Mexican-American War -- the three wars that proceeded the four-year holocaust known ironically as the Civil War - combined, and more than would occur decades later at Pearl Harbor, D-Day, or on September 11th, 2001. And if that scale of carnage is hard to imagine, there are the photographs taken by two of Matthew Brady's employees the next day, the first ever taken of a battlefield before the bodies were removed, to "help". (*SEE PHOTOS BELOW*)

Since its founding in 1890, Antietam National Battlefield has served as an object lesson in the dangers of divisiveness and the horrors of war, lessons that can only be brought home even more poignantly by this month's 150th anniversary. So if you have never been to Antietam, this is definitely the year to go. And if you have, this is the year to go back.

Though no match for Gettysburg in the contemporary national consciousness, Antietam was arguably an even more decisive battle in determining the outcome of the Civil War. In addition, it has the advantage of being among the most easy to visualize: not only did it all take place in a single day, it did so in a more-or-less sequential order starting to the north and ending in the small town of Sharpsburg to the south, a town still very much as provincial and out-of-the-way today as it was a century and a half ago. (In the South, the battle is generally referred to as The Battle of Sharpsburg.)

Grasping the enormity of what did happen here when Union General George McClellan's 60,000 men engaged Robert E. Lee's roughly 40,000 Rebels should begin at the National Park Service's visitor center. A 26-minute film sets up both the battle historically (after thwarting the Union effort to take Richmond in June and roundly defeating them again at Second Bull Run in late August, Lee decided to take the war to the North) and gives a visual idea of the slaughter that was the inevitable result of open line charges against entrenched defensive positions. (An hour-long version is shown daily at noon.) Also on display are artifacts from the battle and five, large panoramic depictions of pivotal moments in the day from the brush of Capt. James Hope, a Vermont landscape painter and participant.

Specific aspects of the battle are covered in guided ranger walks offered throughout the day, but the most practical way of taking in the whole of Antietam is via the self-guided, 8.5-mile driving tour, which takes roughly two hours to complete. Among the most compelling of the 11 designated stops are Miller's Cornfield, where Thomas "Stonewall" Jackson's men held off Union advances for three long hours; the Sunken Road (a.k.a. Bloody Lane) where 2,500 Rebels under D. H. Hill held off nearly five times as many Union infantry, also for three hours, though at great loss; and hilltop-defended Burnside's Bridge, which Union General Ambrose Burnside finally succeeded in storming only to have the impending late-afternoon rout of the Confederate forces saved by the dramatic and providential arrival of General A. P. Hill's brigade of reinforcements after a 17-mile march from Harper's Ferry.

It is widely believed that had McClellan pursued the fleeing Rebels the next day, the war could have been over. (Instead, a truce was declared so that each side could collect its wounded and bury its dead.) But he didn't, and as a result, Antietam turned out to be a draw militarily. McClellan's propensity to procrastinate had previously been criticized by Lincoln, his commander-in-chief, who had once famously written him, "If you don't want to use the Army, I should like to borrow it for a while." This time, however, his hesitation cost the general his command. McClellan would return the favor by running against Lincoln as the Democratic standard bearer in 1864.

Politically, however, Antietam was still a tremendous victory for the Union, ending as it did Lee's first invasion of the North (the second would end at Gettysburg 10 months later). Equally importantly, it effectively eliminated the possibility that European powers would recognize the Confederacy as a separate nation and allowed Northern pro-war candidates to prevail in the Congressional mid-term elections.

Most significantly, however, it prompted President Abraham Lincoln to issue the Emancipation Proclamation four days later, thus unequivocally redefining the year and a half-old conflict as a war against slavery. That more than anything else only hardened Southern resolve not to negotiate, thus guaranteeing dozens more bloody days -- albeit none quite as deadly - to come before the South had no choice but to surrender, and a re-united nation could begin the long process of rebuilding.

Antietam Battlefield