Across the Antietam, three miles from Sharpsburg, to the southeast, is the northern end of Elk Ridge,—a mountain running south to Harper's Ferry, forming the west wall of Pleasant Valley.
The Antietam, below the Boonesboro' road, runs along the western base of the ridge. It is not more than four miles from the Antietam, opposite the head of the ridge, to the great bend in the Potomac, northwest of Sharpsburg. General Lee selected this narrow gate for his line of battle. It had many advantages. It was a short line. It could not be flanked. It was on commanding ground. General McClellan must attack in front. He must cross the Antietam, ascend the steep bank, over ground swept by hundreds of guns, and face a direct as well as a flanking fire. McClellan could not turn the right flank of the Rebels, because there the Antietam runs close to the base of Elk Ridge, then turns due west, and empties into the Potomac. He could not turn the left flank, for there the Rebel army leaned upon the Potomac.
The dotted line passing through Jackson's position is a narrow farm road, along which Jackson erected his defensive works.
Positions of the Two Armies.
The diagram represents the general positions of the divisions as they came upon the field.
| 1 Hooker's corps. 2 Mansfield's corps. 3 Sedgwick's division, Sumner's corps. 4 French's " " " 5 Richardson's " " " 6 Franklin's corps. 7 Porter's corps. 8 Burnside's corps. 9 McClellan's head-quarters. | A. Jackson. B D. H. Hill. C Longstreet. D A. P. Hill. E Lee's head-quarters. |
