|Special Orders 191|
What became known as Special Orders 191 (S.O.191), was formulated by Confederate Robert E. Lee as the Confederate army rested in camps in and around Frederick, Maryland. Issued on September 9th, the orders laid out the plan for the coming days of Lee's campaign as well as for the capture of Harper's Ferry, Virginia (home to a garrison of about 12,000 Union soldiers). Lee had to take Harper's Ferry because his intention was to march farther north and into Pennsylvania but, with this large garrison sitting directly astride is intended line of supply and communication, the Valley Turnpike in the Shenandoah Valley, he could not risk to advance further until the garrison was dealt with.
The plan called for the division of Lee's army: General Thomas "Stonewall" Jackson would lead his command towards Sharpsburg, Maryland and cross the Potomac River at the most convenient point to capture the Baltimore and Ohio Railroad and the garrison at Martinsburg, Virginia while closing in on Harper's Ferry from the Northwest. General James Longstreet, with Lee, would move with the "main body" of the Confederate army to Boonsboro, Maryland. A third part under Lafeyette McLaw's would advance to Middletown, Maryland and then south towards Maryland Heights, closing off Harper's Ferry from the direction. A fourth part would be lead by James Walker would take possession of Loudoun Heights and work with McLaws and Jackson to capture Harpers Ferry. Daniel Harvey Hill (D.H. Hill) would form with his division the rear guard of the army and J.E.B. Stuart with his cavalry would cover the army's advance into western Maryland.
With orders issued, the movement began on September 10th and the capture of Harper's Ferry was to be completed within a few days. The plan fell behind from the start and its outline changed. Jackson, in overall command of the three columns advancing on Harper's Ferry, would not completely encircle Harper's Ferry until September 13th and Lee would accompany Longstreet to Hagerstown to investigate reports of a sizable Union force of Pennsylvania militia advancing on the vital crossroads town. At this point, Lee's army is stretched across the Maryland countryside and barely within range of support of each other, if at all. At this point, with his army divided by miles of roads and even a major river, Lee was unaware of the events occurring in Frederick and the peril his army was in.
One rule of warfare is to not divide your army in the presence of your enemy and Lee had done just that. With the discovery of S.O. 191, McClellan had an idea, despite the orders being four days old, where the Confederate army was in front of him. Jackson was at Harper's Ferry with his division and three others (McLaw's, R.H. Anderson, Walker)and the town was still holding out with telegraphs still coming from the post command Dixon Miles stating that the Confederates were approaching while Longstreet was behind the imposing South Mountain. One of the vital pieces of information missing from the orders was troop strengths so McClellan still believed he was facing a vastly superior enemy. With orders in hand, McClellan made the decision that South Mountain would need to be breached before he could relieve the garrison at Harper's Ferry. From here, Union forces would receive orders to march towards the South Mountain passes at Turner's and Crampton's Gap. It would only be a matter of time before men would clash on the slopes of the mountain.
Why was the discovery of S.O. 191 so significant?
Robert E. Lee believed that the Union army, an army he had thrashed at Second Bull Run, would be too demoralized and beaten to mount an effective campaign to expel him from Maryland. This belief gave him resolve that he could allow his army some days of much needed rest in the vicinity of Frederick, Maryland while he could formulate the next phase of the campaign. The resulting plan would divide his army and unknowingly Lee would put it's survival at risk.
While Lee was resting in Frederick, George B. McClellan was put back into command of the defenses in Washington, D.C. and then again he was put into command of the Army of the Potomac. This Potomac Army was not the same army he had with him during his campaign on the Virginia Peninsula with elements of the defunct Army of Virginia mixed with elements of the original Army of the Potomac. McClellan began his advance out of Washington and September 5, 1862, just days after taking command and while Lee was still crossing his men into Maryland. Moving cautiously, McClellan knew the Confederates where in western Maryland, he was just unsure where and he was tasked with shielding Washington and Baltimore, Maryland from any Confederate advances. McClellan, advancing methodically, was feeling for his opponent with lead elements of his army advancing into Frederick on September 12. The next day would prove to be the first turning point of the campaign when the men of the 27th Indiana discovered Lee's S.O. 191. With the orders rushed to McClellan, verified and intelligence gathered, McClellan stepped up his pressure on the Confederates with the knowledge that Lee had divided his army and here was his opportunity to end the rebellion.
The orders he would issue would lead to the first major battle on northern soil at three mountain gaps on South Mountain at Turner's, Fox's, and Crampton's Gap. The ensuing battle would prove to be stalemated at the northern most of the gaps (Turner's and Fox's) but the fighting around Crampton's Gap would prove to be a major Confederate defeat and the Harper's Ferry Expedition would be put into peril with Lafayette and R.H. Anderson's divisions trapped on Maryland Heights and southern Pleasant Valley with their backs to a garrison at Harper's Ferry and the Potomac. This defeat would cause Lee to ordered a withdrawal to Keedysville, Maryland and was contemplating even going back into Virginia. Lee was nearing the end of his Maryland Campaign. Only word, received late on the night of the 14th, that Jackson would take Harper's Ferry, did Lee order a concentration at Sharpsburg.
Special Orders 191 would prove important in the fact the McClellan discovered the Lee had divided his army. Pushing his advantage lead to the fight on South Mountain that dramatically altered the campaign. The direct impact that the orders had forced a fight for the mountain gaps and put Lee and his army in a perilous position.
Joseph Harsh. Taken at the Flood: Robert E. Lee & Confederate Strategy in the Maryland Campaign of 1862. [Kent State University Press,1999]
Stephen Sears. Landscape Turned Red:Landscape Turned Red: The Battle of Antietam. [Mariner Books, 1983]