By the 3rd of September, 1862, Confederate General Robert E. Lee had decided that the best option for his Country and Army in their battle for independence was to strike North into Federal territory. After informing President Jefferson Davis, he did just that.
Committed to an expedition into Maryland, first Lee had to traverse the Potomac River. The Army of Northern Virginia is generally cited as having crossed at White's Ford (not to be confused with White's Ferry 3.5 miles downstream). An army of that size in fact had to use several fords spanning four days:
Sept. 4, Thursday [map]
Gen. D. H. Hill's division:
Sept. 5, Friday [map]
Gen. Thomas J. Jackson's command:
Sept. 6, Saturday [map]
Gen. James Longstreet's command:
Sept. 7, Sunday [map]
Once across, the army was to concentrate at Frederick as it came up. As a result, Lee's forces were strung out the entire length of the Buckeystown-Frederick road, camping along the roadside as necessary. This movement is widely recorded as the "green corn march" due to Lee's famished men being forced to eat "rations from the stalk" as they advanced on Frederick.
The Army of Northern Virginia then gathered in camps to the south side of Frederick. Lee established his headquarters on the John T. Best farm along the Urbana Pike near the Monocacy River, there joined by Jackson, Longstreet, D.H. Hill and, subsequently, J.E.B. Stuart, all of whom set up headquarters in or adjacent to Best's oak grove from September 6-10. Considering ample rigors of the recent Second Manassas campaign, both the army and its commanders were overdue for a few days rest.
While at Frederick Lee penned his proclamation to the people of Maryland, offering aid and comfort as a liberator sympathetic to their plight rather than as a conqueror. Frederick native and senior Maryland commander in Lee's army, Col. Bradley T. Johnson was appointed provost marshal in his home town and issued his own proclamation, inciting Marylanders to rise in their own defense to threaten federally occupied Baltimore and Washington. When no such rising occurred, Lee then considered other options to the west.
In a letter to President Jefferson Davis, September 8, Lee expressed his wish to elicit sympathy in upcoming Northern midterm elections, as well to incite further impetus for European intervention in the conflict. In another letter next day Lee recorded his decision to move "in the direction of Hagerstown and Chambersburg," his precise objective indistinct. At the same time he viewed the thorny Federal garrisons at Martinsburg and Harpers Ferry as impediments astride his pending line of communication and supply. Known to willingly take risks Lee now formulated his plans, spelling out in detail how his next great gamble would unfold.
On the 9th, amid the momentary peace and tranquility of Best's oak grove, Lee penned his now far-famed Special Orders No. 191 to address these eventualities. In summary, S.O.191 ordered the Army of Northern Virginia be split into two task forces with a total of five elements.
The first task force under Gen. Stonewall Jackson would converge on Harpers Ferry from three directions and lay siege, hoping to reduce the garrison by the 12th:
The second task force, accompanied by Lee in person, was to march behind Jackson and concentrate at Boonsboro, its two components being:
Anticipating speedy reduction of Harpers Ferry, Jackson was ordered to rejoin Lee and Longstreet at Boonsboro via Pleasant Valley, or at Hagerstown via Sharpsburg if Harpers Ferry held out longer.
Confident that Union forces could not reorganize and pursue with sufficient speed to hamper him, Lee willfully broke a basic tenet of the military science: Never divide your forces in the face of a superior enemy. Knowing his adversary Gen. George B. McClellan to be a cautious man, Lee gambled that this trait would persist and so separated the halves of his army by twenty miles. Further throwing caution to the wind, Lee then moved Longstreet's command up the National Turnpike toward Hagerstown, contrary to Longstreet's misgivings, leaving D.H. Hill alone at Boonsboro ill-prepared for close pursuit.
The Army of Northern Virginia marched out of Frederick on the 10th, Jackson's command in the lead. Of all the objectives mandated by S.O. 191, those assigned to Jackson covered the greatest distance. Upon approaching Martinsburg he found that its garrison, under Gen. Julius White, had fled to Harpers Ferry. There White deferred to post commandant Col. Dixon S. Miles. Jackson pursued to School House Ridge confronting Miles' Bolivar Heights defenses. Sealing off all ground lying between the Potomac and Shenandoah rivers, Miles was trapped within his exposed lines. He was then fatally compromised when A.P. Hill's division successfully turned the Union left flank adjacent the Shenandoah. Once Confederate artillery had been manhandled to Maryland Heights and Loudoun Heights, Miles' position became hopelessly untenable.
Miles' direction of the siege was less than inspired, though he permitted his cavalry contingent, under Col. Benjamin S. ("Grimes") Davis, to escape the night of the 14th via pontoon bridge to the road skirting the base of Maryland Heights. Next morning, the 15th, while advancing toward Confederate lines to arrange a surrender, Miles was mortally wounded by shellfire from Loudoun Heights. Later that morning nearly 13,000 Federal soldiers were taken prisoner and paroled. Lee's stumbling block had been eliminated, but three days later than expected.
On the morning of Saturday, September 13, fate stepped in to compromise Lee's plans in mid-stride.
Unaccountably, a misdirected copy of S.O.191 was discovered at Frederick by Corporal Barton W. Mitchell, 27th Indiana Infantry, as his unit halted its probe as spearhead of the Union Twelfth Corps. The culprit who mislaid the "Lost Order" will likely never be known, but its benefit to the Union cause was unmistakable.
McClellan now knew that Lee had divided his army behind South Mountain. In truth Union forces had marched in Lee's wake far faster than imagined, his Ninth Corps crossing over Catoctin Mountain to Middletown before day's close on the 13th. Behind it came the bulk of the Army of the Potomac, rapidly closing the distance.
For reasons known only to himself, McClellan took his time digesting and reacting to the Lost Order. Though it came to hand before noon, not until 3:00 that afternoon did he forward a note to cavalry chief Gen. Alfred Pleasonton bearing a transcript of key paragraphs from S.O. 191, asking that Pleasonton ride into the Catoctin Valley to confirm routes and destinations of Lee's two task forces.
Later that evening McClellan boasted to an old army buddy, Gen John Gibbon, how he would put Lee in a tight place next day, vowing to "pitch into his center" in a divide-and-conquer scenario. McClellan wired exuberant telegrams announcing his windfall to President Abraham Lincoln and Gen. Henry Halleck in Washington, confident that total victory was just a matter of time. To achieve this he would have to force his way over South Mountain through Confederate forces hastily thrown into the South Mountain gaps.
McClellan's reorganized Army of the Potomac was arranged into three wings as it approached from Washington. His right wing - Gen. Ambrose Burnside commanding, Gen. Jesse Reno's Ninth Corps, and Gen. Joseph Hooker's First - moved out of Frederick followed by his center, Gen. Edwin Sumner commanding his own Second Corps and Gen. Joseph Mansfield's Twelfth Corps. These wings had in fact gotten in each other's way as they converged on Frederick. The Ninth Corps of the right wing was already poised in the Catoctin Valley to reconnoiter South Mountain on Sunday, September 14, while the center followed from Frederick on the National Turnpike. In this respect the Lost Order did not alter movements for the bulk of McClellan's army.
Burnside devised and carried out tactical operations at both Turner's and Fox's gaps as right wing commander. On Sunday morning Pleasonton's cavalry struck the first mountain pressure point at Fox's Gap where the Middletown-Keedysville road crosses, closely supported by elements of Reno's Ninth Corps. This was the first combat of the war on Maryland soil. Burnside's design unfolded as a joint extended flanking maneuver spanning two miles of mountain crest for control of the National Turnpike through Turner's Gap. One mile below it, Fox's Gap was to be seized, from which point Ninth Corps troops could then push northward along the summit to force D.H. Hill out of Turner's.
Hooker's First Corps made a remarkable twelve-mile forced march from the banks of the Monocacy River, through Frederick and Middletown on the National Turnpike, to the foot of the mountain via the Old Hagerstown Road, going straight into combat north of Turner's around 4 o'clock.
Burnside delayed deploying his troops in an attempt at coordinated gap assaults however, allowing D.H. Hill barely enough time to race his Confederate brigades, reinforced by those of Longstreet, to each emerging crisis point.
The result was repeated savage head-on collisions, first at Fox's then at Turner's Gap, in what can be described as irresistible forces pitted against immovable objects. Despite heroic obstinacy, Hill's outnumbered 'objects' were nevertheless marginally moved aside by day's harrowing end. A narrow Confederate tactical victory was barely achieved vouching safe Lee's artillery reserve and wagon trains. Firing at both gaps did not cease until about 10 P.M.
Lee reported on the 16th:
"Under General Longstreet's directions, our right [Fox's] was soon restored, and firmly resisted the attacks of the enemy to the last. His superior numbers enabled him to extend beyond both of our flanks, and his right was able to reach the summit of the mountain to our left [Turner's], and press us heavily in that direction. The battle raged until after night; the enemy's efforts to force a passage were resisted, but we had been unable to repulse him."
That night exhausted Confederates resolutely clung to ground from which they could further contest passage through Fox's Gap.
At Turner's Gap the situation seemed irretrievable when Hooker's troops seized and held the summit north of the gap. Lee had virtually nothing left with which to hold the crest line next day.
Weighing his dismal options with Longstreet and Hill that night near Boonsboro, Lee then learned of the last straw at Crampton's Gap six miles to the south.
McClellan's forces marched from Washington on separate roads like splayed fingers on an extended hand, each finger forced inward to converge on Frederick. Turned downward closer to the river, like a thumb at distance from the fingers, was his left wing, Gen. William Franklin's Sixth Corps, hugging the north bank of the Potomac. On the 13th McClellan ordered him northward to Buckeystown away from the river. By evening his corps had encamped at the eastern foot of Catoctin Mountain.
While the Lost Order had little impact on army movements on the National Pike, Franklin's corps got the nod for McClellan's "pitch into" Lee's center. At 6:20 P.M. McClellan forwarded Franklin the longest and most forceful dispatch of the campaign. In it he explained at great length that, knowing Lee's precariously divided posture, he wished Franklin to cross over into the Catoctin Valley to Jefferson, then march to Burkittsville and seize Crampton's Gap, sole conduit to the vacant ground lying between Longstreet and Jackson. In so doing Franklin would relieve Harpers Ferry and, more significantly, drive a mobile wedge between disjointed Confederate halves, allowing McClellan to descend on Lee, Longstreet and Hill with overwhelming numerical superiority. Franklin's actions would be guided by McClellan's success or failure at Turner's Gap. Driving his point emphatically home, McClellan asserted:
"My general idea is to cut the enemy in two and beat him in detail. I ask of you, at this important moment, all your intellect and the utmost activity that a general can exercise....the decisive results I propose to gain."
Instead of moving that evening, Franklin marched at daybreak on the 14th, idled at Jefferson to await arrival of Gen. Darius Couch's division, then pushed on to Burkittsville without Couch, arriving there at noon. He further delayed approach to Crampton's Gap until 4 P.M. attacking at 5:30. The gap was seized by twilight at 6:30. Crampton's Gap was the first undisputed victory over any portion of Lee's army thus far in the war, as well the only unambiguous triumph of the campaign.
Franklin's subsequent failure to relieve Harpers Ferry, or to interpose his forces between the Confederate halves, negated any benefit McClellan derived from acquisition of the Lost Order.
Lee had little choice but to speedily abandon South Mountain:
"Learning later in the evening that Crampton's Gap (on the direct road from Fredericktown to Sharpsburg) had been forced, and McLaws' rear thus threatened, and believing from a report from General Jackson that Harper's Ferry would fall next morning, I determined to withdraw Longstreet and D. H. Hill from their positions and retire to the vicinity of Sharpsburg, where the army could be more easily united."
Lee now faced imminent disaster.
The night hours of September 14-15 were hungry, sleepless, and road-weary for Confederate defenders of South Mountain. Lee had to reach Sharpsburg before the Federal Sixth Corps, anticipating a threat Franklin would hesitate to offer. Confederates quitting Turner's Gap marched overnight through Boonsboro to Keedysville enroute to Sharpsburg. Those abandoning Fox's Gap straggled due west to Keedysville, littering the roadside with utterly exhausted men.
That night Lee resigned himself to leaving Maryland and warned McLaws to evacuate Pleasant Valley by any upriver ford he could find. Next day troops of Longstreet and D.H. Hill collected on high ground between Sharpsburg and Antietam Creek, wary of pursuit.
Gen. Israel Richardson's division, Second Corps, was first to reach the banks of Antietam Creek at the Middle Bridge on the Boonsboro Pike, but displaced upstream to hold the Upper Bridge by which the bulk of McClellan's forces would assemble. In Richardson's wake came Gen. George Sykes' lone division of the Fifth Corps, tasked with holding the Middle Bridge at Lee's center. Here McClellan joined Sykes on the overlooking bluffs to study Lee's stiffening lines.
McClellan stayed his hand throughout Tuesday the 16th, biding his time until the Army of the Potomac closed up from the Catoctin Valley and South Mountain.
On the 15th Lee learned that Harpers Ferry had fallen that morning. Now Jackson was free to join him at Sharpsburg via Shepherdstown Ford. McLaws and Anderson used their escape route through Harpers Ferry, following Jackson to Shepherdstown Ford. The Army of Northern Virginia would be safely whole again.
Encouraged, Lee steeled himself for a last desperate gamble. He would challenge McClellan to a set-piece battle at Sharpsburg hoping to salvage something of value from an expedition gone terribly wrong. The stage was set for a climactic clash of armies.
--- Tim Reese, December 2003, for Antietam on the Web