There were four main reasons Harpers Ferry was a strategic target for the Confederate military:
It was located near the Shenandoah Valley, where the Confederates held ground, and a mere 50 miles from the United States capital, Washington, D.C.
It was built
on the juncture of the Potomac and Shenandoah Rivers, which allowed transport by boat or ferry.
the site of an important railroad bridge, which further increased its
It contained a United States Armory (which was
already famous due to John Brown's raid in 1859), which
promised a sizeable stockpile of arms and ammunition to the side that
could secure it.
Throughout 1862, as Union forces encroached from the west, north, and eastern seaboard, General Jackson led a successful campaign to protect the Shenandoah Valley and avoid Union invasions of Richmond and Fredericksburg. Jackson was familiar with Harpers Ferry. In 1861, he commanded the post at Harpers Ferry under Confederate occupation. In May 1862, he attempted to capture Harpers Ferry but was driven out by Union General Rufus Saxton, who won the Medal of Honor for his actions. By September, Jackson, equipped with a summer of victories in the Shenandoah and knowledge of Harpers Ferry's geography, returned to Harpers Ferry as General Robert E. Lee commenced his first invasion of the North. It was risky for Lee to divide his army with Union General George B. McClellan and the larger Army of the Potomac on his heels, but the Union garrison at Harpers Ferry was worth the risk. It would not only be a major Confederate victory, but it would insure supply lines to Virginia and Lee's army in Maryland would remain open. On September 9, Lee issued Special Orders 191, directing Jackson to Harpers Ferry.2
The attack would come from multiple directions and converge on the insulated town. Harpers Ferry sits in a valley surrounded by steep, forested mountains. Union commander Colonel Dixon S. Miles, failed to realize the importance of the heights surrounding the town. With most of his forces in the town itself, Miles left only a small force at Maryland Heights to protect the surrounding landscape. This would prove disastrous, allowing the Confederates to easily gain the high ground and a tactical advantage. Jackson moved troops from western Maryland to School House Ridge, Brigadier General John G. Walker claimed Loudoun Heights with no opposition, and Major General Lafayette McLaws prepared to take on Union troops at Maryland Heights. The stage was set for a decisive Confederate victory.3
Confederate forces under Major General McLaws first met the Union army at the sparsely defended Maryland Heights, and easily took the position in a brief skirmish. During the struggle for these heights, other Confederate brigades noticed that positions west and south of the town weren't even defended. Seizing the initiative, Jackson placed his artillery all around the town and called Brigadier General A.P. Hill to arm Bolivar Heights. A fierce artillery barrage followed, along with a ground assault, heavily demoralizing the Union garrison. Surrounded by artillery and a force twice their size, Union leaders agreed to surrender the town and garrison on September 15. Miles was mortally wounded that day and the Brigadier General Julius White made the formal surrender, resulting in the capture of over 12,000 Union soldiers.4
Following Confederate victory, Jackson held Harpers Ferry until Lee called on his support in the Battle of Antietam, a bloody struggle on Northern ground that began on September 17. Jackson and his troops rushed to Sharpsburg, Maryland, and Hill was left in charge of processing Union prisoners until he was also called to Sharpsburg. Following the Battle of Antietam, Union troops regained the abandoned Harpers Ferry. The battle was an important Confederate victory that reinforced Jackson's tactical capabilities and bolstered supply lines. In the coming years, Harpers Ferry would flip between Union and Confederate occupation multiple times, demonstrating again its use as a strategic military and transportation post. Today, much of the battlefield is protected by the Harpers Ferry National Historical Park and the Civil War Trust.5