On September 16, 1862, Maj. Gen. George B. McClellan and his Union Army of the
Potomac confronted Robert E. Lee’s Army of Northern Virginia at Sharpsburg, Maryland.  
At dawn on September 17, Maj. General Joseph Hooker’s Union corps mounted a powerful
assault on Lee’s left flank that began the Battle of Antietam, and the single bloodiest day in
American military history. Repeated Union attacks, and equally vicious Confederate
counterattacks, swept back and forth across Miller’s cornfield and the West Woods.
Despite the great Union numerical advantage, Stonewall Jackson’s forces near the Dunker
Church would hold their ground this bloody morning. Meanwhile, towards the center of the
battlefield, Union assaults against the Sunken Road would pierce the Confederate center
after a terrible struggle for this key defensive position.  Unfortunately for the Union army
this temporal advantage in the center was not followed up with further advances.

Late in the day, Maj. General Ambrose Burnside’s corps pushed across a bullet-strewn
stone bridge over Antietam Creek and with some difficulty managed to imperil the
Confederate right. At a crucial moment, A.P. Hill’s division arrived from Harpers Ferry, and
counterattacked, driving back Burnside and saving the day for the Army of Northern
Virginia. Despite being outnumbered two-to-one, Lee committed his entire force at the
Battle of Antietam, while McClellan sent in less than three-quarters of his Federal force.
McClellan’s piecemeal approach to the battle failed to fully leverage his superior numbers
and allowed Lee to shift forces from threat to threat.  During the night, both armies tended
to their wounded and consolidated their lines. In spite of crippling casualties, Lee continued
to skirmish with McClellan on the 18th, while removing his wounded south of the Potomac.
McClellan, much to the chagrin of Abraham Lincoln, did not vigorously pursue the
wounded Confederate army. While the Battle of Antietam is considered a draw from a
military point of view, Abraham Lincoln and the Union claimed victory.  This hard-fought
battle, which drove Lee’s forces from Maryland, Antietam Bridgewould give Lincoln the
“victory” that he needed before delivering the Emancipation Proclamation — a document
that would forever change the geopolitical course of the American Civil War.