Sept. 13 On the 13th Jackson passed through Halltown and halted a mile north of that village,[[15]] throwing out pickets to hold the roads which lead south and west from Harper’s Ferry. Meanwhile, McLaws and Walker had taken possession of the heights to the north and east, and the intrenched camp of the Federals, which, in addition to the garrison, now held the troops who had fled from Martinsburg, was surrounded on every side. The Federal officer in command had left but one brigade and two batteries to hold the Maryland Heights, the long ridge, 1,000 feet high, on the north shore of the Potomac, which looks down on the streets of the little town. This detachment, although strongly posted, and covered by breastworks and abattis, was driven off by General McLaws; while the Loudoun Heights, a portion of the Blue Ridge, east of the Shenandoah, and almost equally commanding, were occupied without opposition by General Walker. Harper’s Ferry was now completely surrounded. Lee’s plans had been admirably laid and precisely executed, and the surrender of the place was merely a question of hours.

Nor had matters progressed less favourably elsewhere. In exact accordance with the anticipations of Lee and Jackson, McClellan, up till noon on the 13th, had received no inkling whatever of the dangerous manœuvres which Stuart so effectively concealed, and his march was very slow. On the 12th, after a brisk skirmish with the Confederate cavalry, his advanced guard had occupied Frederick, and discovered that the enemy had marched off in two columns, one towards Hagerstown, the other towards Harper’s Ferry, but he was uncertain whether Lee intended to recross the Potomac or to move northwards into Pennsylvania. On the morning of the 13th, although General Hooker, commanding the First Army Corps, took the liberty of reporting that, in his opinion, “the rebels had no more intention of going to Pennsylvania than they had of going to heaven,” the Federal Commander-in-Chief was still undecided, and on the Boonsboro’ road only his cavalry was pushed forward. In four days McClellan had marched no more than five-and-twenty miles; he had been unable to open communication with Harper’s Ferry, and he had moved with even more than his usual caution. But at noon on the 13th he was suddenly put into possession of the most ample information. A copy of Lee’s order for the investment of Harper’s Ferry, in which the exact position of each separate division of the Confederate army was laid down, was picked up in the streets of Frederick, and chance had presented McClellan with an opportunity unique in history.[[16]] He was within twenty miles of Harper’s Ferry. The Confederates were more than that distance apart. The intrenched camp still held out, for the sound of McLaws’ battle on the Maryland Heights was distinctly heard during the afternoon, and a resolute advance would have either compelled the Confederates to raise the siege, or have placed the Federal army between their widely separated wings.

But, happily for the South, McClellan was not the man for the opportunity. He still hesitated, and during the afternoon of the 13th only one division was pushed forward. In front of him was the South Mountain, the name given to the continuation of the Blue Ridge north of the Potomac, and the two passes, Turner’s and Crampton’s Gaps, were held by Stuart. No Confederate infantry, as Lee’s order indicated, with the exception, perhaps, of a rear-guard, were nearer the passes than the Maryland Heights and Boonsboro’.[[17]] The roads were good and the weather fine, and a night march of twelve miles would have placed the Federal advanced guards at the foot of the mountains, ready to force the Gaps at earliest dawn. McClellan, however, although his men had made no unusual exertions during the past few days, preferred to wait till daylight.

Nevertheless, on the night of the 13th disaster threatened the Confederates. Harper’s Ferry had not yet fallen, and, in addition to the cavalry, D. H. Hill’s division was alone available to defend the passes. Lee, however, still relying on McClellan’s irresolution, determined to hold South Mountain, thus gaining time for the reduction of Harper’s Ferry, and Longstreet was ordered back from Hagerstown, thirteen miles west of Boonsboro’, to Hill’s assistance.

Sept. 14 On the same night Jackson, at Halltown, opened communications with McLaws and Walker, and on the next morning (Sunday) he made the necessary arrangements to ensure combination in the attack. The Federal lines, although commanded by the Maryland and Loudoun Heights to the north and east, opposed a strong front to the south and west. The Bolivar Heights, an open plateau, a mile and a quarter in length, which has the Potomac on the one flank and the Shenandoah on the other, was defended by several batteries and partially intrenched. Moreover, it was so far from the summits occupied by McLaws and Walker that their guns, although directed against the enemy’s rear, could hardly render effective aid; only the extremities of the plateau were thoroughly exposed to fire from the heights.

In order to facilitate communication across the two great rivers Jackson ordered a series of signal stations to be established, and while his own batteries were taking up their ground to assail the Bolivar Heights he issued his instructions to his colleagues. At ten o’clock the flags on the Loudoun Heights signalled that Walker had six rifled guns in position. He was ordered to wait until McLaws, who was employed in cutting roads through the woods, should have done the same, and the following message explained the method of attack:—

“General McLaws,—If you can, establish batteries to drive the enemy from the hill west of Bolivar and on which Barbour’s House is, and from any other position where he may be damaged by your artillery. Let me know when you are ready to open your batteries, and give me any suggestions by which you can operate against the enemy. Cut the telegraph line down the Potomac if it is not already done. Keep a good look-out against a Federal advance from below. Similar instructions will be sent to General Walker. I do not desire any of the batteries to open until all are ready on both sides of the river, except you should find it necessary, of which you must judge for yourself. I will let you know when to open all the batteries.

“T. J. JACKSON,
“Major-General Commanding.”[[18]]

About half-past two in the afternoon McLaws reported that his guns were up, and a message “to fire at such positions of the enemy as will be most effective,” followed the formal orders for the co-operation of the whole force.

“Headquarters, Valley District,
Sept. 14, 1862.