Immediately following the
Confederate victory at
Second Battle of Bull Run, the South's commander
Robert E. Lee wanted to take the battles to the Northern soil. A year and a half of fighting throughout Northern
Virginia had decimated that state's resources, and Lee wanted his troops to forage for supplies in neighboring
Maryland.
Before heading to Maryland, Lee wanted to ensure his troops' escape route back to the South. He needed to capture the Union outpost at Harper's Ferry whose large garrison of troops could hinder any Southern retreat. To secure his rear, Lee ordered Thomas "Stonewall" Jackson to take Harper's Ferry. The plan called for the invasion to start on September 1, 1862, and for Jackson to have taken Harper's Ferry by September 12, 1862. After Jackson's mission was complete, he was to rejoin Lee's army to face the Union army of Major General George McClellean.
Lee's timetable for Jackson was immediately thrown off course by unexpected and stiff Union resistance at Martinsburg, MD. Jackson did not even reach Harper's Ferry until September, 12. After three days of intense shelling and siege the Union garrison of 11,500 surrended. But Jackson was now behind schedule.
Now came one of the most incredibly lucky invents in this or any war. An Indiana scout fumbled upon (some say literally tripped over) a bundle of three cigars wrapped in a paper which detailed Lee's orders to capture Harper's Ferry. It also gave the position of every Confederate division, and the meeting place for the two halves of Lee's army. As poorly as the Union fared in the battle with this information, it's likely they'd have been completely routed without it.
Lee setup his defensive fortifications on September 16 just to the east of Sharpsburg, MD, less than a mile to their rear was the Potomac River, and just in front was a small creek called Antietam. Lee's army of 26,000 was badly outnumbered by the 70,000 man Army of the Potomac marching toward them. He knew he needed Jackson's return before he could make a stand. He also new that Jackson's men should be there within the day.
The battle began in earnest at 6:00 AM on September 17. With Meade's troops advancing across a high-standing cornfield and the adjoining "West Woods". Meade was repulsed from the cornfield, but part of his men managed to gain a foothold in the "West Woods" and were flanking into the cornfield itself..
Southern Major General John Hood realized his men in the cornfield were about to be badly outflanked and released a full division straight through the cornfield and into the "East Woods" on its farside. This stalemated the cornfield, and by 8:30 in the morning hand to hand fighting was the [order of the day. During the slaughter that followed the North lost two Major Generals, but managed to drive the rebels from the field. An estimated 7,500 casualties resulted from the first two hours of action at Antietam.
With the wounding of I Corps commander Joseph Hooker, both sides withdrew slightly to catch their breath. At about 9:00 the North attempted to consolidate their gain in the cornfield, but Lee's reinforcements had begun to trickle in from Harper's Ferry. The first Northern division sent across the field ran smack into two freshly arrived Southern divisions and was quickly routed. A Union attempt to flank to the southeast also ran into Rebel reinforcements and was beaten back.
Another Northern attempt to flank to the east proved more succesful and soon Yankee cannon fire poured into the eastern edge of the Southern line causing a general retreat. About 10:00 a reformed Southern line held positions just north and west of a bend in Antietam Creek. Union reserves led by Ambrose Burnside were ordered into battle against the new Southern positions.
Burnside sent one of his divisions, south along the creek looking for a place to cross, while he concentrated on taking the "Lower Bridge" that crossed Antietam. Across the bridge sat a well covered Southern brigade that held off wave after wave of Union attempts to the cross the bridge, which forever after became known as "Bloody Burnside Bridge". About 1:00 in the afternoon after three carnage filled hours, Burnside's men took the bridge when a flanking manuver by the troops Burnside had sent south to ford the creek flushed the southerner's from their positions.
With Sharpsburg in sight the Union army marched just to the edge town before being pushed back around 4:00 by the final reinforcements arriving from Harper's Ferry. At about 5:00 the Union retreated to the west edge of Antietam Creek with both sides ending the engagement in the same position held at the beginning of the days fighting.
The 10 hours of fighting left 22,726 total men dead or wounded -- almost 20 percent of the total combatants.