Here are four:
1. The battle is known both as the Battle of Antietam and the Battle of Sharpsburg. The North named most of their battles after natural features (Antietam Creek, Bull Run), while the South tended to name battles after the nearest city or town (Sharpsburg, Manassas).
2. Lee's retreat after the battle took place at a nearby ford over the Potomac. At the time this ford was known as Pack Horse Ford, Blackford's Ford, Boteler's Ford, and Shepherdstown Ford. All are names for essentially the same ford on the Potomac River.
3. Gettysburg was the bloodiest battle of the Civil War. Some 50,000 men fell killed or wounded or were captured at Gettysburg during Lee's second invasion of the North in early July of 1863, but over 3 days, not one. Some 23,000 men were killed, wounded, or captured in Antietam in a single day of battle, thus making it the bloodiest day in American history.
4. The Battle of Antietam was possibly the most important battle of the Civil War. Lee's retirement back into Virginia allowed President Abraham Lincoln to use the Union's strategic victory to issue his Emancipation Proclamation, declaring all slaves held in rebellious states to be free as of Jan. 1, 1863. If there was any real chance that Great Britain or France would intervene on the side of the Confederacy, the Emancipation Proclamation ended that hope. England and France, which had already banned slavery, could no longer take up the Confederate cause.
