September 17, 1862 Units: 1st, 2nd, 5th, 6th 9th, 12th Corps, Couch's Division, 4th Corps Losses: Union - 2,010 killed, 9,416 wounded, 1,043 missing Confederacy - 3,500 killed, 16,399 wounded, 6,000 missing

September 17th, the bloodiest day in American history, with almost 23,000 casualties, as the Confederate Army is stopped at Antietam, Maryland. Although the battle was tactically inconclusive, it had a unique significance as a partial victory that gave President Abraham Lincoln the confidence to announce his Emancipation Proclamation. Lee deployed his Army along Antietam Creek along a low ridge. Jackson defended the north flank, anchored on the Potomac River, James Longstreet defended the south flank, anchored on the Antietam. This was a precarious position because the Confederate rear was blocked by the Potomac River and only a single ford was available if they needed to retreat. McClellan arrived in the area Sept. 16th, but his trademark caution delayed his attack on Lee, giving the Confederates more time to prepare defensive positions and allowed Longstreet's Corps to arrive from Hagerstown and Jackson's Corps, minus A.P. Hill's division, to arrive from Harper's Ferry. On the evening of Sept. 16th, McClellan ordered the 1st Corps, under the command of Maj. Gen. Joseph Hooker, to cross Antietam Creek and probe the enemy positions. George Meade's division of regulars cautiously attacked Confederates, under the command of John B. Hood, near the East Woods. Artillery fire continued long after darkness, as McClellan continued to position his troops. The skirmish in the East Woods served to signal McClellan's intentions to Lee, who prepared his defenses accordingly. At dawn Sept. 17th the battle began with an attack down the Hagerstown Turnpike from the union 1st Corps. Hooker's artillery opened fire on Jackson's men across a cornfield on the Miller's farm. Artillery and gunfire from both sides was so thick it acted like a scythe to cut down not only all the corn stalks, but over 8,000 men on both sides. According to some accounts, possession of the cornfield changed hands up to 15 times that morning.