A few days after Lee crossed into Maryland, McClellan left Washington with seventy-five thousand troops of the Army of the Potomac (which now included troops from Pope's disbanded Army of Virginia). McClellan traveled east in search of Lee, who had divided his fifty-two thousand-man army in order to attack the Federal armory at Harpers Ferry, Virginia (now in West Virginia), located just south of Maryland near the Potomac River. Led by Stonewall Jackson, the Confederate detachment captured the armory on September 15, seizing a huge number of weapons (13,000 rifles and 73 pieces of artillery) and 12,500 prisoners in the process. After grabbing everything that they could carry from Harpers Ferry, Jackson's troops moved back into Maryland in order to rejoin the rest of Lee's army at Sharpsburg, on Antietam Creek.
McClellan, meanwhile, continued to advance his Northern troops forward. He proceeded cautiously until September 13, when he received an incredible stroke of good luck. On that day, a Union soldier found a copy of Lee's military plans wrapped around three cigars lost by a careless Confederate officer. After reviewing
Lee's orders, an excited McClellan increased the speed of his advance in order to catch the Confederates before Lee could reunite his scattered forces.
McClellan's discovery of Lee's secret plans spurred him to close in on the Confederate Army more quickly, but many historians believe that the Union general was still too slow to act. By September 16, most of McClellan's forces had reached the vicinity of Anti-etam Creek. But he held off on launching a major attack until the next day, in part because he seriously overesti mated the size of the Confederate Army stationed there. McClellan's decision to wait saved Lee from a complete disaster, for Stonewall Jackson's detachment did not return to Lee's camp until the evening of the sixteenth.
On the morning of September 17, the two armies finally converged in a vicious day-long battle that killed or wounded more than twenty-three thousand Union and Confederate soldiers. This one-day casualty toll marked the single bloodiest day in Civil War history. Throughout the morning and afternoon, Union regiments roared forward through a hail of rebel gunfire in brave attempts to break through the Confederate defenses. The Federal troops destroyed many Southern regiments, but Lee's men refused to give way. This desperate courage impressed even the Union soldiers who attacked them. "It is beyond all wonder," said one Union veteran of Antietam, "how such men as the rebel troops can fight on as they do; that filthy, sick, hungry, and miserable, they should prove such heroes in fight, is past explanation."
When darkness finally fell on the battlefield, both armies withdrew in exhaustion, leaving behind thousands of dead and wounded soldiers. The next morning Lee held his position, as if daring McClellan to resume the fight. But McClellan stayed put, and on the evening of September 18, Lee gathered the remains of his army together and slipped back into Virginia.
The Battle of Antietam (called the Battle of Sharpsburg in the South)
thus ended in a strangely inconclusive way, with neither side able to claim a clearcut victory. But while the battle itself had ended in a bloody draw, the clash marked a major turning point in the Civil War. Lee's invasion of the North had ended in failure, and his Army of Northern Virginia had sustained terrible damage. Moreover, the Battle of Antietam provided the people of the North with badly needed reassurance that the war might yet go their way. Finally, it gave Lincoln the opening he needed to issue his famous Emancipation Proclamation.
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