Antietam, Battle of

Bloody but indecisive battle of the American Civil War on 17 September 1862 at Antietam Creek, off the Potomac River. Maj-Gen George McClellan of the Union blocked the advance of the Confederates under General Robert E Lee on Maryland and Washington, DC. This battle paved the way for Abraham Lincoln's proclamation of emancipation, and also persuaded the British not to recognize the Confederacy.

The Confederates were aiming north toward Harrisburg, intending to destroy a rail bridge and then see what further opportunity was offered. Lee halted at Frederick, sending a detachment off to deal with the Union garrison at Harpers Ferry while he pushed on to Hagerstown. Unfortunately McClellan obtained a discarded copy of Lee's orders and he dispatched the Union Army toward the gap between Lee's two forces. After a skirmish with McClellan's leading troops, Lee fell back to Sharpsburg to await his detachment's return from Harpers Ferry, taking up a defensive line along the Antietam Creek east of Sharpsburg, about 16 km/10 mi north of Harpers Ferry. The Union Army closed in but did not attack until the following day. By noon on 17 September both sides had fought themselves to a standstill, but then the Confederate detachment from Harpers Ferry came up just as the Union forces brought up fresh troops. More bitter fighting ensued but the Union commander, General Charles Sumner, believing that further Confederate reinforcements were arriving, decided that further attacks were useless. McClellan ordered a flanking attack by General Ambrose Burnside's corps, but more Confederates arrived from Harpers Ferry just in time to take this attack in its flank. This proved to be the final engagement: both armies spent the night gathering their wounded, and on the following day each waited for the other to attack. Neither did, and Lee was able to withdraw his force and make his way back to Virginia.

Antietam was the bloodiest battle of the Civil War: the Confederates lost 2,700 dead, 9,000 wounded, and 2,000 missing out of 51,844 troops; the Union forces lost 2,100 dead, 9,500 wounded, and 750 missing out of 75,316 troops.