It remains the single bloodiest day of fighting on American soil, and it was fought 150 years ago this week in the Civil War: The Battle of Antietam began Sept. 17, 1862, when Union forces commanded by Maj. Gen. George B. McClellan clashed with Confederate rivals under the direction of Gen. Robert E. Lee in a cornfield at Sharpsburg, Md., or Antietam.
Marked by attacks and counterattacks, the pitched 12 hours of fighting claimed at least 23,000 wounded, missing and disappeared.
When the roar of combat was over, Lees limping Army of Northern Virginia was forced to withdraw on Sept. 18 amid final skirmishing to cross the Potomac River southward to the safety of Virginias Shenandoah Valley.
Neither side could claim this as an outright tactical victory. Yet Antietam was, nonetheless, a turning point in the Civil War and seized upon as a strategic victory for the Union. The federal forces, although they failed to pursue Lees retreating army, had shown they could stop the savvy Confederate commanders opening invasion of the North.
Historically, the battles aftermath gave President Abraham Lincoln the moment he needed to roll out his preliminary Emancipation Proclamation. Within days, Lincoln would declare that the Civil War had the double aim of keeping the Union intact and abolishing slavery.