On Saturday, September 13th, 1862, the 27th Indiana Infantry Regiment, part of the Union XII Corps was camped just outside of Frederick, Maryland near Myer's Farm. Corporal Barton W. Mitchell of Company F saw something a bit out of the ordinary next to a fence alongside of the road. Curious, he walked over and noticed that it was a somewhat bulky package. Upon opening it he saw 3 cigars wrapped in paper. Unwrapping the cigars, he read the paper.
Considering it important, he showed it to his sergeant, who then passed it on up through military channels until it ended up in the hands of Major General George B. McClellan, commander of the Army of the Potomac.
It was a copy of Confederate General Robert E. Lee's plan for the invasion of Maryland, and it provided detailed information of the disposition of his forces.
Lee had entered Maryland on September 3rd following his victory at the Second Battle of Bull Run. It was hoped by both Lee and Jefferson Davis, the Confederate President, that a southern victory on northern soil would affect public opinion in the north.
Davis also hoped that such a victory might even bring recognition and financial support from England and France.
And Lee hoped to gather more supplies for his army. There was also a possibility of picking up recruits from the sympathetic Marylanders.
By September 13th, Lee's 55,000 man army was essentially scattered between Hagerstown Maryland to the north and Harpers Ferry to the south.
So McClellan was quite naturally ecstatic about receiving this "lost plan" from Lee. He had the information needed to defeat Lee in detail.
But he waited a precious 18 hours before he acted on the intelligence.
Once Lee was informed that one of his plans intended for his field commanders was missing, he acted swiftly by sending out couriers with VERBAL orders to consolidate his forces around Sharpsburg, Maryland.
Just to the east of town there was a good defensive position along and west of Antietam Creek. Lee had only 18,000 men with him at this time, but he was counting on speedy reinforcement.
McClellan and his 90,000 man Army of the Potomac arrived in the area on the evening of September 15th.
If he had attacked right then and there, McClellan could have destroyed Lee's force, but again, he hesitated; thinking that Lee had more men than he did.
At any rate, the delay gave Lee more time to prepare his defenses.
On the evening of September 16th, McClellan ordered Hooker's I Corps to cross Antietam Creek and probe Lee's left flank.
McClellan plan was to overwhelm this flank with three or possibly even four corps.
At 5:30am on September 17th, the attack began. Hooker's troops came out of the North Woods and entered a corn field -- their objective being the plateau on which sat the Dunker Church.
An exchange of artillery fire began the battle.
The Union troops saw the Confederates who were also in the cornfield, and brought up more artillery.
Now the artillery was aimed at the infantry, as both sides were mowed down by shell after shell.
Hooker had numerical superiority but instead of massing his forces, he attacked piecemeal, sending brigade after brigade into the fray one at a time -- a pattern that was to be repeated by Union generals all day long.
The cornfield changed hands no fewer than 15 times, leaving behind a horrific scene of death, destruction and devastation. But the Union army was making progress -- if at frightful casualties to both sides.
Confederate reinforcements arrived around 7:00am, and counterattacked. By 7:30am, they had driven Hooker's men back to their original starting positions.
Two more Union corps were thrown into the fray, but the attacks were not properly coordinated, the only result being more casualties.
Now the battle shifted to the center of Lee's line.
A division of Union troops who had, for one reason or another strayed from the formation attacking the flank, was in position opposite the Confederate center. It was now ordered to attack in an attempt to draw off Confederate forces from the flank.
The position being attacked was a sunken road on the top of a gradual ridge. After this day, it would be known forever as "Bloody Lane".
Once again, the attack was made one brigade at a time. Each one being chewed up by a whithering fire and forced to retreat. The fourth attack was made by the famous Irish Brigade. After losing more than 500 men, they too were forced to withdraw.
Another Union brigade arrived on the scene, but this time it swung around to the right of the Confederate position on the sunken road.
From a slight rise, they began to pour a murderous fire down on the defenders who were now trapped in the sunken road.
Other Union troops arrived and finished the job.
For all intents and purposes, the center of the Confederate line was now broken. Lee shifted his troops. Also, a command change in the attacking Union formation sapped the momentum of the attack. The Confederate line was restored, again at frightful loss of life.
Now it was the turn of the Confederate right flank.
It was at this place that Antietam Creek was the closest to the Confederate lines. High bluffs overlooked the creek. The creek was fordable further south, but there was a stone bridge in the area.
McClellan wanted General Ambrose Burnside's IX Corps to launch a diversionary attack in this sector -- still hoping to crush Lee on his left.
Scouting parties reported to Burnside that Antietam Creek could be forded just a short distance down stream, avoiding the necessity of a frontal assault across the bridge.
Burnside opted for the frontal assault.
The bridge was relatively narrow. Four men could walk abreast across it. It was a bottleneck -- easily defended.
Nevertheless, after several attempts, and murderous casualties, Burnside managed to get a force across the creek and started advancing up and beyond the bluffs towards Sharpsburg.
Lee's army was beginning to crumble under the constant pressure from a superior force and was forced to fall back all along the line.
Then, at 3:30 in the afternoon, just in the nick of time, Confederate General A.P. Hill's division of fresh troops arrived from Harpers Ferry and struck Burnside's advancing troops head on, forcing Burnside to give way.
Burnside sent a message to McClellan asking for more troops, but even though McClellan had a reserve corps on hand, he informed Burnside that there were none to spare.
Arrangements were now made to remove the dead and tend to the wounded, but by 5:30, the battle was essentially over.
On the morning of September 18th, Lee prepared for an attack by McClellan which never came.
Lee was able to extricate his army across the Potomac and back into Virginia, McClellan never seriously interfering.
Antietam was the bloodiest single day in the history of American warfare. The Union had suffered over 12,000 casualties, while the Confederates had over 10,000. This represented 25% of the Union force, and 31% of the Confederate force.
Although, technically the battle was considered to be draw, and McClellan should have won a victory, at least it wasn't another defeat.
President Lincoln felt that the time was now suited to issue his Emancipation Proclamation.
From now on the War Between the States would take on a higher meaning. Freedom.
