Dawn on 17 September 1862 broke grey and misty over the Maryland farmland around Sharpsburg, and within hours it would become the deadliest single day the United States had ever known. By nightfall an estimated 22,000 to 23,000 men lay killed, wounded or missing along the banks of a quiet stream called Antietam Creek. Two great armies, General Robert E. Lee's Army of Northern Virginia and General George B. McClellan's Army of the Potomac, had thrown themselves at one another across cornfields, a sunken country lane and a narrow stone bridge, and when the guns fell silent the ground itself seemed changed forever.
Lee Carries the War North
Flush with victory after the Second Battle of Bull Run, Lee gambled on a bold stroke: he would carry the war out of ravaged Virginia and onto Northern soil for the first time. An invasion of Maryland might draw the border state to the Confederate cause, feed his hungry army from Union fields, and perhaps convince Britain and France to recognise the young Confederacy. But the campaign turned on a stunning accident. Union soldiers discovered a copy of Lee's Special Order 191, the so-called Lost Orders, wrapped around three cigars in an abandoned camp. The document laid bare that Lee had divided his army into scattered columns. Handed this rare gift, the usually cautious McClellan now knew exactly how vulnerable his opponent was, though he would move too slowly to fully exploit it.
The Cornfield and the Sunken Road
The battle opened at first light in Miller's cornfield on the northern end of the field, where Union and Confederate lines surged back and forth through stalks cut down as if by a scythe. The fighting there was so ferocious that men later recalled the corn being clipped level with the ground by bullets, and the dead lay in rows where they had stood. To the south, Confederate troops packed into a worn farm lane that history would rename the Bloody Lane, or Sunken Road. For roughly three hours they held this natural trench against wave after wave of Union assaults, until attackers finally gained a position that let them fire straight down the length of the lane. The slaughter in that sunken track was appalling, yet even after breaking the centre the Union command hesitated to press its advantage.
Burnside's Bridge and a Battle Undecided
On the southern flank, Union General Ambrose Burnside spent much of the day struggling to force a crossing of Antietam Creek at a narrow stone span thereafter known as Burnside's Bridge. A mere few hundred Georgia riflemen on the high bluff above held off far larger numbers for hours, and only in the early afternoon did Union troops finally storm across. Just as Burnside's men pushed toward Sharpsburg and threatened to cut Lee's line of retreat, the Confederate general A. P. Hill arrived after a punishing forced march from Harpers Ferry and slammed into the Union flank, halting the advance. As darkness fell the two exhausted armies still faced each other, neither having landed a decisive blow. Tactically, the day had ended in a bloody stalemate.
An Inconclusive Field, a Turning Point
Lee held his ground through the following day, daring McClellan to renew the attack, but the Union commander, ever overcautious, did not. That night Lee withdrew his battered army back across the Potomac into Virginia. Because Lee abandoned his invasion and retreated, the North could rightly claim Antietam as a strategic victory, even though McClellan failed to destroy the Confederate army when he had the chance. The consequences reached far beyond the battlefield. President Abraham Lincoln had been waiting for a Union success to announce a measure he had already drafted, and Antietam gave it to him. Five days later he issued the preliminary Emancipation Proclamation, transforming the war's purpose and warning that enslaved people in rebelling states would be declared free from the first day of 1863.