“Had General Lee remained in front of Washington (south of the Potomac) it would have been the part of wisdom to hold our own army quiet until its pressing wants were fully supplied, its organisation was restored, and its ranks were filled with recruits—in brief, until it was prepared for a campaign. But as the enemy maintained the offensive, and crossed the Upper Potomac to threaten or invade Pennsylvania, it became necessary to meet him at any cost, notwithstanding the condition of the troops, to put a stop to the invasion, to save Baltimore and Washington, and throw him back across the Potomac. Nothing but sheer necessity justified the advance of the Army of the Potomac to South Mountain and Antietam in its then condition. The purpose of advancing from Washington was simply to meet the necessities of the moment by frustrating Lee’s invasion of the Northern States, and when that was accomplished, to push with the utmost rapidity the work of reorganisation and supply, so that a new campaign might be promptly inaugurated with the army in condition to prosecute it to a successful termination without intermission.”[[30]]
And in his official report, showing what the result of a Confederate success might well have been, he says: “One battle lost and almost all would have been lost. Lee’s army might have marched as it pleased on Washington, Baltimore, Philadelphia, or New York. It could have levied its supplies from a fertile and undevastated country, extorted tribute from wealthy and populous cities, and nowhere east of the Alleghenies was there another organised force to avert its march.”[[31]]
3. The situation in the West was such that even a victory in Maryland was exceedingly desirable. Confederate movements in Tennessee and Kentucky had won a measure of success which bade fair to open up a brilliant opportunity. Should the Federals be defeated in both the theatres of war, the blow would be felt throughout the length and breadth of the Northern States; and, in any case, it was of the utmost importance that all McClellan’s troops should be retained in the East.
So, when the tidings came of Jackson’s victory at Harper’s Ferry, both armies braced themselves for the coming battle, the Confederates in the hope that it would be decisive of the war, the Federals that it would save the capital. But the Confederates had still a most critical time before them, and Lee’s daring was never more amply illustrated than when he made up his mind to fight on the Antietam. McClellan’s great army was streaming through the passes of the South Mountain. At Rohrersville, six miles east of the Confederate bivouacs, where he had halted as soon as the cannonade at Harper’s Ferry ceased, Franklin was still posted with 20,000 men. From their battle-field at Turner’s Gap, ten miles from Sharpsburg, came the 70,000 which composed the right and centre; and on the banks of the Antietam but 15,000 Southerners were in position. Jackson had to get rid of his prisoners, to march seventeen miles, and to ford the Potomac before he could reach the ground. Walker was twenty miles distant, beyond the Shenandoah; and McLaws, who would be compelled by Franklin’s presence near Rohrersville to cross at Harper’s Ferry and follow Jackson, over five-and-twenty. Would they be up before McClellan attacked? Lee, relying on McClellan’s caution and Jackson’s energy, answered the question in the affirmative.
The September day wore on. The country between the South Mountain and Sharpsburg, resembling in every characteristic the Valley of the Shenandoah, is open and gently undulating. No leagues of woodland, as in Eastern Virginia, block the view. The roads run through wide cornfields and rolling pastures, and scattered copses are the only relics of the forest. It was not yet noon when the Federal scouts appeared among the trees which crown the left bank of the Antietam Creek. “The number increased, and larger and larger grew the field of blue until it seemed to stretch as far as the eye could see. It was an awe-inspiring spectacle,” adds Longstreet, “as this grand force settled down in sight of the Confederates, shattered by battles and scattered by long and tedious marches.”[[32]] But when night fell upon the field the only interchange of hostilities had been a brief engagement of artillery. McClellan’s advance, owing to the difficulty of passing his great army through the mountains, and to the scarcity of roads, had been slow and tedious; in some of the divisions there had been unnecessary delay; and Lee had so disposed his force that the Federal commander, unenlightened as to the real strength of his adversary, believed that he was opposed by 50,000 men.
Sept. 16 Nor was the next morning marked by any increase of activity. McClellan, although he should have been well aware that a great part of the Confederate army was still west of the Potomac, made no attack. “It was discovered,” he reports, “that the enemy had changed the position of some of his batteries. The masses of his troops, however, were still concealed behind the opposite heights. It was afternoon before I could move the troops to their positions for attack, being compelled to spend the morning in reconnoitring the new position taken up by the enemy, examining the ground, and finding fords, clearing the approaches, and hurrying up the ammunition and supply trains.”[[33]]
Considering that McClellan had been in possession of the left bank of the Antietam since the forenoon of the previous day, all these preliminaries might well have been completed before daylight on the 16th. That a change in the dispositions of a few batteries, a change so unimportant as to pass unnoticed in the Confederate reports, should have imposed a delay, when every moment was precious, of many hours, proves that Lee’s and Jackson’s estimate of their opponent’s character was absolutely correct. While McClellan was reconnoitring, and the guns were thundering across the Antietam, Jackson and Walker crossed the Potomac, and reported to Lee in Sharpsburg.[[34]] Walker had expected to find the Commander-in-Chief anxious and careworn. “Anxious no doubt he was; but there was nothing in his look or manner to indicate it. On the contrary, he was calm, dignified, and even cheerful. If he had had a well-equipped army of a hundred thousand veterans at his back, he could not have appeared more composed and confident. On shaking hands with us, he simply expressed his satisfaction with the result of our operations at Harper’s Ferry, and with our timely arrival at Sharpsburg; adding that with our reinforcements he felt confident of being able to hold his ground until the arrival of the divisions of R. H. Anderson, McLaws, and A. P. Hill, which were still behind, and which did not arrive till next day.”[[35]]
Yet the reinforcements which Jackson and Walker had brought up were no considerable addition to Lee’s strength. Jones’ division consisted of no more than 1,600 muskets, Lawton’s of less than 3,500. Including officers and artillery, therefore, the effectives of these divisions numbered about 5,500. A. P. Hill’s division appears to have mustered 5,000 officers and men, and we may add 1,000 for men sick or on detached duties. The total should undoubtedly have been larger. After the battle of Cedar Run, Jackson had 22,450 effectives in his ranks. His losses in the operations against Pope, and the transfer of Robertson’s cavalry to Stuart, had brought his numbers down by 5,787; but on September 16, including 70 killed or wounded at Harper’s Ferry, they should have been not less than 16,800. In reality they were only 11,500. We have not far to look for the cause of this reduction. Many of the men had absented themselves before the army crossed into Maryland; and if those who remained with the colours had seen little fighting since Pope’s defeat, they had had no reason to complain of inactivity. The operations which resulted in the capture of Harper’s Ferry had been arduous in the extreme. Men who had taken part in the forced marches of the Valley campaign declared that the march from Frederick to Harper’s Ferry surpassed all their former experiences. In three-and-a-half days they had covered over sixty miles, crossing two mountain ranges, and fording the Potomac. The weather had been intensely hot, and the dust was terrible. Nor had the investment of Harper’s Ferry been a period of repose. They had been under arms during the night which preceded the surrender, awaiting the signal to assault within a few hundred yards of the enemy’s sentries. As soon as the terms of capitulation were arranged they had been hurried back to the bivouac, had cooked two days’ rations, and shortly after midnight had marched to the Potomac, seventeen miles away. This night march, coming on the top of their previous exertions, had taxed the strength of many beyond endurance. The majority were badly shod. Many were not shod at all. They were ill-fed, and men ill-fed are on the highroad to hospital. There were stragglers, then, from every company in the command. Even the Stonewall Brigade, though it had still preserved its five regiments, was reduced to 300 muskets; and the other brigades of Jackson’s division were but little stronger. Walker’s division, too, although less hardly used in the campaign than the Valley troops, had diminished under the strain of the night march, and mustered no more than 3,500 officers and men at Sharpsburg. Thus the masses of troops which McClellan conceived were hidden in rear of D. H. Hill and Longstreet amounted in reality to some 10,000 effective soldiers.
It was fortunate, indeed, that in their exhausted condition there was no immediate occasion for their services on September 16. The shadows grew longer, but yet the Federals made no move; even the fire of the artillery died away, and the men slept quietly in the woods to north and west of the little town. Meanwhile, in an old house, one of the few which had any pretensions to comfort in Sharpsburg, the generals met in council. Staff officers strolled to and fro over the broad brick pavement; the horses stood lazily under the trees which shaded the dusty road; and within, Lee, Jackson, and Longstreet pored long and earnestly over the map of Maryland during the bright September afternoon. But before the glow of a lovely sunset had faded from the sky the artillery once more opened on the ridge above, and reports came in that the Federals were crossing the Antietam near Pry’s Mill. Lee at once ordered Longstreet to meet this threat with Hood’s division, and Jackson was ordered into line on the left of Hood. No serious collision, however, took place during the evening. The Confederates made no attempt to oppose the passage of the Creek. Hood’s pickets were driven in, but a speedy reinforcement restored the line, and except that the batteries on both sides took part the fighting was little more than an affair of outposts. At eleven o’clock Hood’s brigades were withdrawn to cook and eat. Jackson’s division filled their place; and the night, although broken by constant alarms, passed away without further conflict. The Federal movements had clearly exposed their intention of attacking, and had even revealed the point which they would first assail. McClellan had thrown two army corps, the First under Hooker, and the Twelfth under Mansfield, across the Antietam; and they were now posted, facing southward, a mile and a half north of Sharpsburg, concealed by the wood beyond Jackson’s left.