The Army of the Potomac, under the command of George McClellan, mounted a series of powerful assaults against Robert E. Lee’s forces near Sharpsburg, Maryland, on September 17, 1862. The morning assault and vicious Confederate counterattacks swept back and forth through Miller’s Cornfield and the West Woods. Later, towards the center of the battlefield, Union assaults against the Sunken Road pierced the Confederate center after a terrible struggle. Late in the day, the third and final major assault by the Union army pushed over a bullet-strewn stone bridge at Antietam Creek. Just as the Federal forces began to collapse the Confederate right, the timely arrival of A.P. Hill’s division from Harpers Ferry helped to drive the Army of the Potomac back once more. The bloodiest single day in American military history ended in a draw, but the Confederate retreat gave Abraham Lincoln the “victory” he desired before issuing the Emancipation Proclamation. After pursuing Confederate General Robert E. Lee into Maryland, Union Army Maj. Gen. George B. McClellan launched attacks against Lee's army, in defensive positions behind Antietam Creek. At dawn on September 17, Maj. Gen. Joseph Hooker's corps mounted a powerful assault on Lee's left flank. Attacks and counterattacks swept across Miller's cornfield and fighting swirled around the Dunker Church. Union assaults against the Sunken Road eventually pierced the Confederate center, but the Federal advantage was not followed up. In the