Battle of Antietam summary

The Battle of Antietam also known as the Battle of Sharpsburg was fought on Wednesday, September 17, 1862, near Sharpsburg, Maryland, and Antietam Creek, as part of the Maryland Campaign.

1. Near the town of Sharpsburg, Lee deployed his available forces behind Antietam Creek along a low ridge, starting on September 15. While it was an effective defensive position, it was not an impregnable one. The terrain provided excellent cover for attacking infantrymen and the creek to their front was only a minor barrier.It was a dangerous position because the Confederate rear was blocked by the Potomac River and only a single crossing point was nearby should retreat be necessary.
2. The battle opened at dawn (about 5:30 a.m.) on September 17 with an attack down the Hagerstown Turnpike by the Union I Corps under Joseph Hooker. As the first Union troops came close to the enemy, an artillery duel erupted.
3. Union infantry attacked in limited numbers but gained little ground due to the lack of reinforcements.
4. By midday, the Union forces turned their efforts to the center of the Confederate line. The first Union attack conducted mainly by inexperienced troops failed.
5. Reinforcements arrived on both sides with Lee committing his final reserve division.
6. Finally Union troops broke through and advanced.
7. Massed artillery hastily assembled by Gen. Longstreet and a counterattack drove them back. However if this broken sector of the Confederate line were exploited, Lee's army would have been divided in half and possibly defeated. But Union commander McClellan hated risks and the chance was lost.
8. The action moved to the southern end of the battlefield. Maj. Gen. Ambrose Burnside and the IX Corps were facing Confederate forces that had been greatly depleted by Lee's movement of units to bolster the Confederate left flank. Burnside's men made three attacks and finally with the help of low Confederate ammunition managed to secure the bridge.
9. Burnside's assault now stalled again on its own. His officers had neglected to transport ammunition across the bridge, which was itself becoming a bottleneck for soldiers, artillery, and wagons. This represented another two-hour delay. Gen. Lee counted on the arrival of A.P. Hill's Light Division, currently embarked on an exhausting 17 mile (27 km) march from Harpers Ferry.
10. Burnside's men attacked and started to move forward unaware that 3,000 new men would be facing them.
11. Hill's Light Division attacked and collapse of his left flank, Burnside ordered his men all the way back to the west bank of the Antietam, where he urgently requested more men and guns. McClellan was again too cautious to give more support and the chance for a breakthrough was lost.
12. On the morning of September 18, Lee's army prepared to defend against a Federal assault that never came. After an improvised truce for both sides to recover and exchange their wounded, Lee's forces began withdrawing across the Potomac that evening to return to Virginia.