America’s Bloodiest Day (Not September 11)

Confederate dead by a fence on the Hagerstown Road, September 1862

(LIBRARY OF CONGRESS LC-B811-560)

Almost a century and a half later, September 17, 1862, remains the bloodiest day in American history. The Battle of Antietam, fought near the Maryland town of Sharpsburg that day, claimed the lives of more Americans than all the U.S. wars of the nineteenth century combined except the Civil War. Estimates vary as to the exact number who died that day; some say around 6,500, others even more. All together nearly 23,000 were killed or wounded in the monumental clash between the armies of Generals George B. McClellan and Robert E. Lee. And their deaths changed the course of the Civil War.

Antietam was certainly not the only pivotal battle of the war, but it took place at a moment when the Union was desperate for a victory, even a narrow and hard-won one, as the Confederacy threatened to overwhelm President Lincoln’s efforts to reunify his nation. McClellan’s strategic victory shattered Lee’s invasion of Maryland and reverberated internationally to strengthen the Northern cause.

Just three weeks before, the Union war effort had suffered what appeared to be a crippling defeat at the Second Battle of Manassas. At the end of August, Lee had led the Confederate Army of Northern Virginia into battle against a Union army commanded by Major General John Pope. With Major General Thomas “Stonewall” Jackson at his side, Lee successfully fought the numerically superior Union force into submission, leaving some 3,300 dead and more than 17,000 wounded. Lee’s victory over Pope brought the Confederacy into a position of unmistakable dominance in the almost two-year-old war, and it opened the way for Lee’s invasion of Maryland, which would bring him to Antietam in mid-September. The Second Battle of Manassas was a terrific slaughter. One soldier who served there lamented afterward: “This was the very vortex of Hell.” That soldier, like General Lee, could hardly have imagined that a day far bloodier and a battle still more hellish would check the progress of the Southern rebellion.

As he surveyed the field at Antietam, Lee had to know that his troops were in many ways at a disadvantage. The Union held a strong upper hand in sheer numbers, although that had never proved an insurmountable obstacle for Lee in the past. More troubling was the persistent difficulty the Confederate forces faced in adequately equipping themselves. In a September 3 letter, Lee warned Confederate President Jefferson Davis that “this army is not properly equipped for an invasion of the enemy’s territory.” Many of his men were poorly armed and clothed, and the Army of Northern Virginia entered Northern territory with a troubling lack of food. Lee tried to remedy these problems by allowing his men to pillage in Maryland and, more significantly, by dividing his army in order to let Stonewall Jackson capture a set of Union supply centers. Both of these moves may have harmed his cause. Lee’s original hope that Maryland would welcome his invasion and side with the South went unrealized, and Jackson’s delay in reaching the battlefield at Sharpsburg initially left Lee with a relatively weak force on hand.

Stephen Sears’s 1989 American Heritage article “The Terrible Price of Freedom” gives a detailed account of the troop movements and stages of fighting that took place on the Antietam battlefield and brings September 17, 1862, to life in all its harsh reality. At the end of the day, with the waning of combat, the tide of battle had turned—just barely—in favor of McClellan’s men, but at a terrible cost. Only days afterwards, the bloodied ground at Antietam was documented by Alexander Gardner and James Gibson, two photographers working for Mathew Brady’s New York Studio. The scenes their cameras captured appalled those who visited their galleries. Antietam’s devastation was on a scale previously unseen, with much of it concentrated right at the center of Lee’s lines. The distorted bodies of horses reflected the enormous toll taken on cavalry. Soldiers reported tales of horrifically wounded men begging their own officers to kill them, and the officers obliging.

But McClellan’s victory, however bitterly won, was invaluable to the Northern campaign. Its back broken, Lee’s Army of Northern Virginia withdrew from Maryland and terminated its costly invasion of the North. What had appeared to be a fast-paced march to victory and a separatist peace had ended at the battle of Antietam, demonstrating that Southern secessionists would not achieve their aims so quickly or easily as they might have hoped after Second Manassas. Perhaps the greatest virtue of this demonstration was its resonance overseas. Many members of the English elite and the British press had long harbored Confederate sympathies. After Second Manassas William Gladstone, the Chancellor of the Exchequer, nearly persuaded the prime minister, Lord Palmerston, to move to recognize the Confederate claim to sovereignty and mediate a truce. The news of Antietam convinced many British observers that the war would be a stalemate, and to many this suggested that mediation was more necessary than ever, but the uncertain outcome of possible British intervention raised enough doubt to delay the actions of pro-Southern English politicians.

The Battle of Antietam also led to one of the best-known and most celebrated Presidential actions in American history: the Emancipation Proclamation. The previous July, Lincoln had been rebuffed by border state leaders in his efforts to secure an agreement by which slaves would be emancipated and their owners compensated. Frustrated, he informed several advisors, including Secretary of State William Seward, that he intended to use Presidential war powers to liberate Southern slaves. Seward advised him to wait until the Union army won a significant victory, to avoid letting emancipation look like a desperate President’s attempt to foment a slave revolt. Considering this advice wise, Lincoln waited. When Antietam presented him with the hoped-for military victory, he let only a few days pass before he warned the Confederacy of his intention to issue the proclamation with the coming of the new year. Thus the bloodiest day in American history gave way to one of its most benevolent.

—Alexander Burns, an undergraduate at Harvard College, is a frequent contributor to AmericanHeritage.com