Battle of South Mountain

Battle of South Mountain
(Battle of Boonsboro Gap)

Fox's Gap at the battle of South Mountain, MD. Sunday, Sept. 14, 1862

Date	September 14, 1862
Location	Frederick County and Washington County, near Boonsboro, Maryland 39°29′06″N 77°37′18″W / 39.48501°N 77.62161°W / 39.48501; -77.62161Coordinates: 39°29′06″N 77°37′18″W / 39.48501°N 77.62161°W / 39.48501; -77.62161
Result	Union victory

Belligerents

United States (Union)

CSA (Confederacy)

Commanders and leaders

George B. McClellan
Ambrose Burnside
William B. Franklin

Robert E. Lee
D.H. Hill

Strength

28,000

18,000

Casualties and losses

2,325 total
(443 killed, 1,807 wounded, 75 missing)

2,685 total
(325 killed, 1560 wounded, 800 missing)

The Battle of South Mountain—known in several early Southern accounts as the Battle of Boonsboro Gap—was fought September 14, 1862, as part of the Maryland Campaign of the American Civil War. Three pitched battles were fought for possession of three South Mountain passes: Crampton's, Turner's, and Fox's Gaps. Maj. Gen. George B. McClellan, commanding the Union Army of the Potomac, needed to pass through these gaps in his pursuit of Confederate General Robert E. Lee's precariously divided Army of Northern Virginia. Although the delay bought at South Mountain would allow him to reunite his army and forestall defeat in detail, Lee considered termination of the Maryland Campaign at nightfall.

South Mountain is the name given to the continuation of the Blue Ridge Mountains after they enter Maryland. It is a natural obstacle that separates the Hagerstown Valley and Cumberland Valley from the eastern part of Maryland.

After Lee invaded Maryland, a copy of an order, known as order 191, detailing troop movements that he wrote fell into the hands of McClellan. From this, McClellan learned that Lee had split his forces, sending one wing under Maj. Gen. Thomas J. Jackson to lay siege to Harper's Ferry. The rest of Lee's army was posted at Boonsboro under command of Maj. Gen. James Longstreet. Lee hoped that after taking Harper's Ferry to secure his rear, he could carry out an invasion of the Union, wrecking the Monocacy aqueduct, before turning his attention to Baltimore, Philadelphia, or Washington D.C. itself. McClellan hoped to attack and defeat Lee's isolated forces before they could concentrate against him. To reach Lee, McClellan had to move across South Mountain.

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Wikipedia