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The Significance of the Battle of Antietam

"What America is and hopes to be dates from the fight along Antietam Creek. The fight cost an enormous number of lives, and inflicted pain and disability on many thousands more; but in the infinite economy of the advance of the human race it may have been worth what it cost."
- Bruce Catton, in American Heritage, August 1958

So what's the big deal about the Battle of Antietam, anyway? What makes it so fascinating? How did it affect the participants? The course of the War? The future of the Nation?

This page will try to briefly answer these questions hoping to put Antietam in perspective, and to show why it was one of the great battles in American history.

Immediate Results of the Battle

The most obvious result of the battle was the incredible loss of life. No other single day of American history before or since has been so deadly. Nearly one of every four soldiers engaged was a casualty: killed, wounded, or captured. The savage fighting would be remembered by many who were there as the most intense of the war. If there were any among the troops who still thought of war as a glorious, noble undertaking, this battle would shatter that illusion. For the men of both armies, the American Civil War was now an all-out, life or death struggle.

star See more about ... Casualty statistics

For the North, the battle near Antietam Creek "saved" the nation. The Confederate invasion was turned away, so the immediate threat was past. In the process, the Federal Army of the Potomac (AOP) had shown itself to be a fine fighting force, especially after it's poor showing in the previous months' campaigning. It had not been demoralized as was feared after the Second Battle of Bull Run, and had in many instances at Antietam proved in bravery and skill to be the equal of any army, anywhere. Even their commander, MGen George McClellan , had not fully appreciated their capabilities. Although the battle was not a clear victory for either side, the forces of the Union had much to feel good about.

Robert E. Lee's Army of Northern Virginia (ANV) had also fought extremely well, particularly considering its weakened state and smaller numbers. Many consider that Lee's leadership at the battle was the best of his career; he himself indicated as much after the war. While he could rightly claim a "moral" victory because he still held his position the day after the battle, he did not achieve his larger goal of seriously hurting the Federal Army, and the Maryland Campaign did little to advance the cause of Southern Independence after all.

star See more about ... Why Lee Invaded Maryland

Another short-term effect of the battle was the final end to President Lincoln's patience with his top General. Because McClellan was not prepared to pursue the ANV for some six weeks after the battle, when prompted repeatedly, Lincoln "fired" him. McClellan then retired to his home in New Jersey to wait for the call to command again, which never came. Lincoln appointed Ambrose Burnside to relieve McClellan in command of the AOP, but Burnside was just the next of the several failures in that position. McClellan had built the AOP into a superb force, and his troops adored him, but he didn't exhibit the killer instinct or drive that would have been needed to win the war for the Union in 1862.

Opportunities Lost?

These are among of the most fascinating things about the battle.

General McClellan was given a copy of General Lee's plans (Special Orders No. 191) on the 13th of September, but it was not enough. It is interesting to speculate on how he might have acted differently, and "crushed" the scattered parts of the ANV one at a time. Instead, Lee was able to complete the capture of Harpers Ferry and gather his army at Sharpsburg before McClellan brought his army to bear.

star See more about ... Lee's Special Orders No. 191

Once at Sharpsburg late on the 15th, McClellan probably lost an opportunity by not attacking Lee immediately, though he would have had to attack without knowing his enemy's strength and position. Lee's forces were not concentrated fully until early on the 17th, when the last (except for A. P. Hill's) Divisions of Jackson Corps arrived on the field from Harpers Ferry. Even on the 17th, McClellan's AOP fought the Confederates in a piecemeal fashion, one Division at a time. This gave Lee time to move his men to the hot spots as needed without worrying too much about the rest of his line.

Further, McClellan failed to "follow success" on the field by not committing his reserves where just "one more push" might have broken the Confederate position. It's fair, however, to consider that it's only in hindsight that we know just how bare was Lee's Center by mid-day on the 17th, where little more than a few batteries of artillery stood to face the Federals once the Sunken Road position was lost. McClellan was more concerned about protecting Washington and his army from a feared (but non-existant) Rebel counterattack than destroying the enemy. McClellan kept about one third of the AOP, about 30,000 men, in reserve that day and the next.

On September 18th, the Union lost another chance. Instead of retreating, as perhaps he should have done, Lee stayed in his positions. Despite having the numbers (including about 30,000 fresh troops), with more on the way, McClellan decided not to renew the attack. Lee slipped back across the Potomac to Virginia that night and early the next morning largely unmolested. Except for a short bloody scrap at Shepherdstown, in which the Federals were repulsed, McClellan did not actively pursue Lee for nearly 6 weeks thereafter.

Lee, too, suffered disappointment on the Maryland campaign. Except for the capture of a large quantity of stores, ordnance, and Union soldiers at Harpers Ferry, he did not have much to show for his efforts. He did hold the field after the battle, and did inflict more casualties than he took, but these were not really enough for the battle at Sharpsburg to be considered a Confederate victory. The morale of the ANV remained high, but they did not get their decisive fight.

Public and Political Impact

For observers in England and France, the Confederate failure in Maryland meant there would be no quick end to the War, and also meant that the Confederacy would have to get along without any help from their governments. While perhaps only a temporary setback for the Confederates, the battle in fact killed the last hope for foreign intervention on behalf of the rebels. Once Lincoln had issued the Emancipation Proclamation (see below), no civilized nation would side against the "defenders of freedom".

The battle had political ramifications in the North as well. Because Lincoln could claim a victory, and it looked as though the fortunes of war might be turning in favor of the Union, the Fall elections of 1862 went rather better for Lincoln's Republican Party (and "War" Democrats) than might have been the case. Lincoln later credited the battle with saving a number of northern and western governor's and legislative seats that otherwise would have gone to "Peace" Democrats, who were opponents of Lincoln's war policy and advocates of a negotiated peace with the South.

The ordinary citizens in the North also felt the impact of the battle in a way not known before in America. A display of Alexander Gardner's Antietam Photographs in New York, and their further publication in newspapers, vividly brought home to them the dreadful carnage of the battle. Like the soldiers who fought, the people who saw these images lost any grand notions of the glory of war, and perhaps better understood something of the reality. The photographs and stories about the fierce combat at Sharpsburg helped many people to begin to understand the effort and sacrifice it was going to take to win the war.

Union and Freedom

As an extension of the change in the public perception of war, the overall strategy of the North began to evolve toward the concept of "total war". While this process was not complete after Antietam, the trend was clear: most people would eventually recognize that the Union could only be restored following the complete destruction of the South's ability to wage war and survive independently. It would no longer be possible to go back to the way things were, or peacefully co-exist with a separate South.

Lastly, but most importantly, the small victory that Lincoln could claim for the battle of Antietam was enough for him to issue the Emancipation Proclamation. While its impact seemed small at first, the enormity of its scope soon became apparent.

star See more about ... The Emancipation Proclamation

The Emancipation Proclamation substantially altered the character of the war from Restoration of the Union alone, to freedom for all. As Catton said,

"It finally determined that the Civil War was not merely a war for reunion but also a war to end human slavery; turned it from a family scrap into an incalculable struggle for human freedom ..."


This is the legacy of Sharpsburg.