Battle of Antietam
After the loss at the second Bull Run Pope was running back to Washington with Lee hot on his tail. However, McClellan heard of his advance and was going to attempt to head him off before Lee got a chance to touch Washington. Not only were there large strategic and political purposes of this campaign, but on the way there Lee and his soldiers hoped to capture supplies for both soldiers, weapons, and animals. After Lee had crossed the Potomac, McClellan finally cut him off at Frederick, Maryland, on the twelfth. The next day one of McClellan's men found a box of cigars which contained the notes for all of Lee's plans. Now McClellan new every move that Lee was going to make but could this general really beat Lee?
Aug. 29-30, 1862
McClellan vs. Lee
Mystery still surrounds the loss of Special Order 191. That it was picked up at Frederick, Maryland, by Private Mitchell of the 27th Indiana on September 13 and delivered promptly to McClellan's headquarters is clear, but who was responsible for its loss is not known. During the next day Lee learned that his note had been dropped and would have rearranged his troops if he could have and then attacked McClellan from a different angle.
According to the Lost Order Lee was going to split his army. Jackson was going to capture Harper's Ferry with 25,000 men, while Lee moved westward toward Sharpsburg in fear of being cut off from Jackson. Between McClellan and Lee were two low-lying ranges, South Mountain and Elk's Ridge; the easiest roads through these were at Turner's Gap and Crampton's Gap. In both places there was heavy Confederate resistance but with McClellan huge army they brushed the small forces away.
On September 15 Lee got word that Jackson had captured Harper's Ferry and was returning to join Lee's army again. With this encouraging news Lee decided to continue on with his plans and take Antietam.
The battle was fought just south of Sharpsburg along the Antietam River. McClellan held both sides of the river while Lee's army was concentrated between Sharpsburg and the Antietam River. For Lee it was his worst strategical position ever, for he had several exposed flanks due to the river. If McClellan had been able to fold up Lee's right flank he could have cut Lee off from the South and possible even have destroyed Lee's army.
The battle was fought only by the small divisions and brigades instead of full fledged attacks, which was a very large advantage for Lee. Now Lee was dealing with sections of McClellan's power house instead of the whole force. There were three major attacks launched by McClellan. The first one was lead by Hooker who attacked Lee's left flank making very little progress. Second, Sumner made a drive on the Confederate center; third, Burnside attempted to cross the river to attack the right flank.
The battle was not a decisive one but it could have been. If either army had been able to destroy one or the other than it could have caused a major shift in the war and most likely a much sooner end of the war.