Antietam site of single bloodiest day of war

Sept. 17, 1862, was the bloodiest single day of the Civil War as the two armies engaged suffered a total of almost 23,000 casualties (killed, wounded and missing or captured). Six other battles produced more casualties, but they were multi-day affairs.

Readers of the Democratic Banner had found out the week before that Gen. Robert E. Lee’s Confederate army was marching into Maryland, but with what objective?

They opened the Sept. 23 edition and immediately saw the news of the Union victories on South Mountain. Then they turned inside and saw the headline:

“The Greatest Battle of the War!”

“Glorious Victory Over the Rebels!

“Longstreet’s Entire Division Captured”

“Reported Capture of 15,000 Rebels!

“Harper’s Ferry Recaptured by Gen. Burnside”

The unsigned dispatch carried by the Banner was dated Sept. 17 and came from Washington:

At 3 o’clock this evening intelligence was received that since 5:30 this morning the fiercest and most sanguinary battle of the whole war has been in progress. All the corps de armee which McClellan had taken with him to Frederick were massed at the point indicated, and the engagement is believed to have been between the whole of the two armies, There is reason to suppose the losses on each side are very great, as the requisition for medical stores and arrangements for wounded men to be sent to Rokersville immediately are larger than have ever been made at any time.

“Information has been received that McClellan had destroyed the aqueduct at the mouth of Antietam Creek and the bridge across that creek up the road leading to Sharpsburg, thus cutting off retreat in the direction of Shepardstown.

“Later reports from Hagerstown state that this afternoon the rebels are retreating in great disorder and subsequently heavy and rapid firing was heard in the direction of Wlliamsport, which induces the belief that McClellan has pursued the retreating rebels to that point, that they made a stand there to cover their passage across the Potomac.”

Further down in the report, obviously written by someone who had no idea of what really happened near Sharpsburg, Md.,: “The battle lasted until 4 o’clock this afternoon, when the rebels retreated, leaving Longstreet and the remnant of his division in our hands as prisoners. The entire rebel army will be captured or killed. There was no chance left for them to cross the Potomac, as the river is rising and our troops are pushing them continually and sending prisoners to the rear. ...

“Burnside has re-taken possession of Harper’s Ferry, and is advancing on a special mission with his corps.”

McClellan missed a huge opportunity at Antietam. At Frederick a few days before, a copy of Lee’s orders, laying out his plan of operations, fell into McClellan’s hands. With swift action he could have caught Lee with his forces divided and crushed the Confederate army. Instead, McClellan frittered away an entire day before sending his army in pursuit of Lee.

First, he had to clear the passes over South Mountain. The push succeeded, but Gen. D.H. Hill was able to delay the Union advance enough that Lee was able to reassemble most of his army at Sharpsburg. Gen. A.P. Hill was still at Harper’s Ferry, paroling the Union garrison, and wouldn’t rejoin Lee until the afternoon of Sept. 17, at a critical moment in the battle.

Once McClellan got over the mountain and confronted Lee, he attacked piecemeal, starting on his right in what became known as the Cornfield. The Dunker Church was near there, while in the center was the Sunken Road, while on the left is Burnside’s Bridge.

Because the Union attacks were not coordinated, Lee was able to shift his outnumbered army to meet the next attack.

But it was a close-run thing. Union attacks cracked the center of Lee’s line, but were not exploited. Burnside was sweeping around the Confederate right when he ran head-on into A.P. Hill’s division from Harper’s ferry.

The Union Fifth Corps and the cavalry were never in the fight.

The battle was tactically a draw, but Lee had to retreat, and so was enough of a Union victory to enable President Lincoln to issue the preliminary Emancipation Proclamation.

Lecky Harper’s reaction to that will be fascinating to read.