The Battle of Antietam: Conflict, Outcome & Significance

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  • 0:07 1862
  • 0:46 Maryland
  • 1:30 General McClellan
  • 2:38 September 17, 1862
  • 3:48 Burnside Bridge
  • 5:25 Lesson Summary
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Lesson Transcript
Instructor: Daniel Vermilya
The Battle of Antietam was fought on September 17, 1862. It was the bloodiest single day battle in American history, with over 23,000 casualties. The Union victory there led to the Emancipation Proclamation.


September 1862 was a dramatic month in American history. The American Civil War was well into its second year, and the Confederate States of America was coming close to winning the conflict and establishing its independence. Many things hung in the balance as Confederate General Robert E. Lee and his Army of Northern Virginia launched a bold and daring invasion into Maryland during that month. The end result of the invasion was the Battle of Antietam, one of the most important days of the Civil War. Antietam was the bloodiest single-day battle in American history, and the Union victory there led to the Emancipation Proclamation.


During the summer of 1862, Confederate armies had found a strong footing and began pushing back invading Union forces. In Virginia, this push led to the Battle of Second Manassas, also known as Bull Run, in late August, a major Confederate victory that was one of the most impressive battles of the war for Lee and his army. Lee decided it was time to take the war to the enemy and launch an invasion of the North. Maryland would serve as Lee's target; it was a state which was still in the Union, yet portions of Maryland sympathized with the Confederate cause. By September 6th, the Confederates were in Frederick, Maryland, and they soon split up to capture a Union garrison at Harpers Ferry.

In pursuit of this invading Confederate force was the Union Army of the Potomac, led by Major General George Brinton McClellan. McClellan was loved by his men but did not get along well with President Abraham Lincoln. Despite the disagreements between Lincoln and McClellan, the general known as the 'Young Napoleon' was tasked with stopping Lee's force. Lincoln wanted a victory badly, because a few months earlier he had decided to issue an emancipation proclamation, freeing all those slaves held in the southern states in rebellion. If McClellan could defeat Lee in Maryland, Lincoln decided he would be ready to issue this important document.

On September 14th, Union troops caught the Confederates largely off guard when they attacked at South Mountain, just west of Frederick. This battle was a Union victory, and it forced Lee and the Confederates to reconsider their campaign. Soon, the Confederates would regroup and fall back to the sleepy farming town of Sharpsburg, where they would form a defensive line. A few days later, the Battle of Antietam was fought.

September 17, 1862

The Battle of Antietam was fought entirely in one day - September 17th, 1862. It is most famous as being the bloodiest single day in American history. The fighting began very early in the morning that day when Union soldiers started attacking the left flank of the Confederate army. This part of the battle raged around a farmer's cornfield, and thus is simply known as 'The Cornfield' today. It was the bloodiest and most confusing part of the battle, with over 8,000 casualties in just a few hours.

The fighting at Antietam also occurred around an old sunken farm road. Confederates holding the road used it to stop numerous waves of Union attackers before they were driven from the position. This road is known today as 'Bloody Lane.' The fight for these locations was a part of the Union army's attempt to crush the left flank of the Army of Northern Virginia. When the fighting for the northern half of the field began to die down in the early afternoon hours of September 17th, there were already over 17,000 casualties from these assaults alone.

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