ANTIETAM 561 by the Rockville turnpike, the right wing of his army extending toward the Baltimore and Ohio railroad, and the left toward the Potomac. His advanced guard entered Frederick as the confederate rear guard was leaving it. At this place, on Sept. 12, he became acquainted with the disposition of Lee's forces, as well as with his immediate plans, through a copy of Lee's marching orders which one of the con- federate commanders had inadvertently left behind him. Lee, having captured all the out- lying detachments of the national army, in- . eluding that in the stronghold of Harper's Ferry, and thus secured his communication with Richmond, concentrated all his available forces, choosing his position in front of Sharps- burg, in the angle between the Potomac, which covered his rear, and the Antietam, whose deep bed and precipitous sides covered his front. Lee's line, forming almost a semicircle about the village, covered all the roads con- centrating at that place ; its right wing rested on the heights dominating the creek, and stretched along it, sweeping all the crossings for more than half a mile ; the centre occupied the open fields and patches of wood extending to the Hagerstown road, and the left rested upon the Potomac. McClellan's army ap- proached the battlefield along the turnpike leading from Keedysville to Sharpsburg, his main body going into position on the left bank of the Antietam on the afternoon of Sept. 15. No fighting took place on this day. The great- er part of the 16th was passed in harmless cannonading, but late in the afternoon McClel- lan threw forward Hooker's corps, with orders to force a passage of the Antietam by the upper one of the four stone bridges spanning the creek in that neighborhood. This bridge, being beyond the reach of the confederate line, had been left undefended, and Hooker's cross- ing was therefore quickly and easily made. Pushing forward at once through a narrow piece of woods, he soon struck the confederate left under Hood, and after a sharp skirmish, terminating with nightfall, in his favor, his corps rested on their arms near the Hagers- town road, almost in contact with the enemy's line. This advance served to place one corps of 18,000 men in a good position to give battle as well as to uncover the other crossings of the Antietam as far down as the Keedysville road, thus rendering it easy for McClellan to secure his initiatory movement, by sending Mansfield's 12th corps, under cover of dark- ness, to strengthen Hooker. On the morning of the 17th the disposition of the combatants was as follows : Lee's position was substantial- ly unchanged; his entire army, estimated at about 65,000 strong, was formed in a semi- circular line covering the roads converging at Sharpsburg. Hooker's and Mansfield's corps of McClellan's army had crossed the Antietam and held advanced positions on the extreme right ; Sumner's corps held itself in readiness to cross ; Porter's corps was in reserve, cover- 87 VOL. i. 37 ing the Keedysville bridge, but separated from the enemy by the creek ; and Burnside's corps occupied the extreme left, and was also sep- arated from the confederate position by the Antietam. The aggregate strength of these corps was about 85,000 men; but being partly on one side and partly on the other side of a stream which could hardly be crossed any- where except by a bridge, and which was particularly easy to defend, the superior strength of the Union army counted but for little in the bloody conflict which followed. McClellan's plan was for Hooker and Mans- field, supported by Sunnier, to attack the con- federate line, and engage it so closely as to permit Burnside, advancing simultaneously, to force a passage at the lower bridge, and thus unite all the corps except the reserve on the further side of the Antietam, with their entire strength available for the final struggle. Hook- er's corps held a position close to the enemy's line, and was therefore forced to begin skir- mishing almost as soon as it was light. After gaming some slight advantages it attacked with great fury, and succeeded in forcing Lee's left under Jackson backward for nearly half a mile before it received the slightest check. Hooker gave his men a short breathing spell, and dashed forward again; but his divisions were already fatigued as well as greatly shat- tered by their bloody work. Meeting the reserves of the enemy's left, they were in turn driven back to the position from which they advanced less than an hour before, notwith- standing Mansfield had in the mean time has- tened forward to join in the conflict. This gallant veteran lost his life in trying to regain the ground lost by Hooker, and, although aided by a terrible fire from the reserve artil- lery of the Union army, stationed near the Keedysville bridge, his corps was also forced to retire to the position from which it had ad- vanced. McClellan now ordered Sumner to advance, and this resolute commander accord- ingly made his appearance on the battlefield about 9 o'clock, and with all the precision of a parade moved his corps of four divisions against the confederate line, over a part of the field somewhat to the left of that covered by Hooker and Mansfield, but directed mainly against the woods to the west of the Dunker church on the Hagerstown road. The con- federates, having had time to rectify and strengthen their lines, received this formidable attack with steadiness ; but so fierce was the onset of Sumner's right division under Sedg- wick, that the confederate division confronting him was driven back into and beyond the woods, when it was strongly reenforced by troops which had arrived upon the field only that morning. The confederates now made a spirited counter attack, directing their move- ment mainly against Sedgwick, who was in echelon with the other divisions of Sumner's corps, and therefore poorly supported by them. The fighting which ensued was characterized
