On September 16th, 1862, the Army of the Potomac, commanded by George B. McClellan, met Robert E. Lee's Army of Northern Virginia along Antietam Creek in Sharpsburg, Maryland. The battle began at dawn on September 17th when General Hooker's men attacked Lee's left flank. Chaos broke out with a series of attacks and counterattacks from both sides. The fighting at that time was mainly located around Dunker Church and through Miller's cornfield. Finally, the Union troops made their way to the Confederate center along what is known as the Sunken Road, but did not actually gain a real advantage until General Burnside's troops crossed Antietam Creek and attacked the Confederate right. At this point, A.P. Hill's troops had arrived from Harper's Ferry and brought the battle to another standstill. The battle continued into the night and all the way into September 18th. Finally, right after dusk on the 18th, General Lee decided to withdraw his troops across the Potomac, ending one of the bloodiest battles of American History.