The Antietam, hardly worthy the name river, is a sluggish stream coming down from Pennsylvania heights in a flow a little west of south till it nears the Potomac, when it bends westward to its confluence. It is spanned by four stone bridges,—at the Williamsport turnpike, the Boonsborough-Sharpsburg turnpike, the Rohrersville turnpike, and another near its mouth. The third was afterwards known as the Burnside Bridge. From the north suburbs of Sharpsburg the Hagerstown turnpike leads north a little west two miles, when it turns east of north to the vanishing point of operations. A mile and a half from Sharpsburg on the west of this road is the Dunker chapel, near the southern border of a woodland, which spreads northward half a mile, then a quarter or more westward. East of the pike were open fields of corn and fruit, with occasional woodlands of ten or twenty acres, as far as the stream, where some heavier forests cumbered the river banks. General Lee’s line stood on the Sharpsburg Heights, his right a mile southeast of the village, the line extending parallel with the Hagerstown turnpike, three miles from his right, the left curved backward towards the rear, and towards the great eastern bend of the Potomac, near which were the cavalry and horse artillery. Along the broken line were occasional ridges of limestone cropping out in such shape as to give partial cover to infantry lying under them. Single batteries were posted along the line, or under the crest of the heights, and the battalions of the Washington Artillery, Cutts’s, and S. D. Lee’s.
In forming his forces for the battle, General McClellan divided his right wing, posted the Ninth Corps on his left, at the Burnside Bridge, under General Cox, and assigned the First Corps, under General Hooker, for his right flank. General Burnside was retained on his left. The plan was to make the main attack against the Confederate left, or to make that a diversion in favor of the main attack, and to follow success by his reserve.
At two P.M. of the 16th, Hooker’s First Corps crossed the Antietam at the bridge near Keedysville and a nearby ford, and marched against my left brigades, Generals Meade, Ricketts, and Doubleday commanding the divisions, battalions, and batteries of field artillery. The sharp skirmish that ensued was one of the marked preliminaries of the great battle; but the Federals gained nothing by it except an advanced position, which was of little benefit and disclosed their purpose.
General Jackson was up from Harper’s Ferry with Ewell’s division and his own, under Generals Lawton and Jones. They were ordered out to General Lee’s left, and took post west of the Hagerstown turnpike, the right of his line resting on my left, under Hood, Winder’s and Jones’s brigades on the front, Starke’s and Taliaferro’s on the second line, Early’s brigade of Ewell’s division on the left of Jackson’s division, with Hays’s brigade for a second; Lawton’s and Trimble’s brigades were left at rest near the chapel; Poague’s battery on Jackson’s front; five other batteries prepared for action. Following Jackson’s march to the left, General J. G. Walker came up with his two brigades, and was posted on my extreme right in the position left vacant by the change of Hood’s brigades.
General Hooker was joined, as he marched that afternoon, by his chief, who rode with him some little distance conversing of pending affairs. It subsequently transpired that Hooker thought the afternoon’s work ordered for his corps (thirteen thousand) so far from support extremely venturesome, and he was right. Jackson was up and in position with two divisions well on the flank of the attack to be made by Hooker. Hood with S. D. Lee’s batteries received Hooker’s attack, and arrested its progress for the day. If Jackson could have been put into this fight, and also the brigades under J. G. Walker, Hooker’s command could have been fought out, if not crushed, before the afternoon went out. He was beyond support for the day, and the posting along the Antietam was such—we will soon see—as to prevent effective diversion in his favor. Events that followed authorize the claim for this combination, that it would have so disturbed the plans of General McClellan as to give us one or two days more for concentration, and under that preparation we could have given him more serious trouble.
Hood’s skirmish line was out to be driven, or drawn in, but throughout the severe engagement his line of battle was not seriously disturbed. After night General Jackson sent the brigades of Trimble and Lawton, under General Lawton, to replace Hood’s men, who were ordered to replenish ammunition, and, after getting food, to resume their places on my right. Preparing for battle, General Jackson sent the brigade under General Early to support Stuart’s cavalry and horse artillery, and Lawton drew his brigade, under General Hays, to support his others on the right of Jackson’s division.
General Mansfield crossed during the night with the Twelfth Corps and took position supporting General Hooker’s command, with the divisions of Generals A. S. Williams and George S. Greene, and field batteries.
A light rain began to fall at nine o’clock. The troops along either line were near enough to hear voices from the other side, and several spats occurred during the night between the pickets, increasing in one instance to exchange of many shots; but for the most part there was silence or only the soft, smothered sound of the summer rain over all that field on which was to break in the morning the storm of lead and iron.