Antietam, Battle of, on Sept. 17, 1862, was the bloodiest single day of the American Civil War (1861-1865). The battle took place in northwestern Maryland. It is named after Antietam Creek, which runs through the battlefield. The battle is also called the Battle of Sharpsburg, after a nearby town. General George B. McClellan led a Union army of about 90,000 troops. McClellan’s army defeated Robert E. Lee’s Confederate army of about 55,000. Soon after the battle, President Abraham Lincoln issued the preliminary Emancipation Proclamation. The proclamation led to the end of slavery in the United States.
In August 1862, the Confederacy won an important victory at the Second Battle of Bull Run in Virginia. That battle is also called the Second Battle of Manassas. In the fighting, Confederate forces under Lee defeated Union forces led by General John Pope. After the battle, Lee decided to invade Maryland. He planned the invasion partly in an effort to keep Union troops out of Virginia. The Confederates also hoped to gain European recognition by winning a victory in Union territory.
Lee divided his army. He sent about half of his soldiers with General Stonewall Jackson to Harpers Ferry, Virginia. Union troops occupied Harpers Ferry. McClellan had replaced Pope as commander of the Union army. McClellan moved to meet Lee’s troops with about 90,000 troops. On September 13, a Union soldier found a copy of Lee’s orders to his officers. The orders were wrapped around three cigars at an abandoned Confederate campsite. Lee learned that the orders had been lost. He took up a position at Sharpsburg, Maryland, a town on Antietam Creek. McClellan had important advantages. He knew Lee’s plans. He also had an army much larger than Lee’s force at Sharpsburg. But he did not immediately attack.
On September 15, the Union forces at Harpers Ferry surrendered to Stonewall Jackson. Jackson left Harpers Ferry with his troops and joined Lee at Sharpsburg. Confederate General A. P. Hill stayed behind at Harpers Ferry to oversee the surrender of the Union troops.
On September 17, McClellan attacked Lee. But, because McClellan had waited to attack, Jackson’s troops were there to reinforce Lee. McClellan ordered small, separate attacks. The Confederates moved troops from one part of the battlefield to another to meet these attacks.
At 6 a.m., Union General Joseph Hooker attacked the Confederates. He pushed toward Dunker Church at the northern end of the battlefield. But Stonewall Jackson stopped his push. Jackson also stopped two other Union attacks. In about five hours of fighting, these three attacks killed or wounded about 7,000 Union soldiers. About 5,000 Confederate soldiers were killed or wounded during the attacks.
At about 10 a.m., south of Dunker Church, Union troops attacked Confederates. The Confederate line ran along Sunken Road—a road that came to be known as the “Bloody Lane.” After fierce fighting, the Union troops drove the Confederates out of the road. But there were not enough Union troops to go any farther. McClellan chose to hold back reinforcements that might have overwhelmed the Confederates.
South of the Bloody Lane, Antietam Creek separated the Union and Confederate troops. Union General Ambrose E. Burnside concentrated his attacks on one stone bridge. He attacked the bridge even though there were shallow places to cross nearby. Burnside’s tactics allowed a small Confederate force to delay a much larger Union force. After about three hours, Burnside captured the bridge and advanced to the other side of the creek. Burnside spent another two hours reorganizing his force. Finally, he pushed forward and closed in on Lee. Just as Burnside approached Lee, General Hill’s troops arrived from Harpers Ferry. They pushed Burnside back toward Antietam Creek. The Union advance stopped, and the battle ended.
Despite being heavily outnumbered, Lee and his army remained on the battlefield. The following day, McClellan chose not to renew the attack. Lee retreated to Virginia with almost no interference. President Lincoln became dissatisfied with McClellan. Lincoln blamed his general for not pursuing Lee after Antietam. In November, Lincoln named Burnside to replace McClellan.
Antietam was the most deadly single day of the Civil War. About 2,000 Northerners and 2,700 Southerners were killed. About 19,000 soldiers from both sides were wounded. About 3,000 of them later died as a result of their wounds. Because Lee retreated, the North considered Antietam a Union victory. On September 22, Lincoln issued the preliminary Emancipation Proclamation. Lincoln had been waiting for a Union military victory before issuing the proclamation. He did not want it to be viewed as a desperate act.
