An obstinate struggle now ensued for the possession of the main South Mountain Gap, near Boonsboro, and the roar of Jackson’s artillery from Harper’s Ferry must have prompted the assailants to determined efforts to force the passage.  The battle continued until night (September 14th), and resulted in heavy loss on both sides, the brave General Reno, of the United States army, among others, losing his life.  Darkness put an end to the action, the Federal forces not having succeeded in passing the Gap; but, learning that a column of the enemy had crossed below and threatened him with an attack in flank, General Lee determined to retire in the direction of Sharpsburg, where Jackson and the forces cooeperating with him could join the main body of the army.  This movement was effected without difficulty, and Lee notices the skill and efficiency of General Fitz Lee in covering the rear with his cavalry.  The Federal army failed to press forward as rapidly as it is now obvious it should have done.  The head of the column did not appear west of the mountain until eight o’clock in the morning (September 15th), and, nearly at the same moment ("the attack began at dawn; in about two hours the garrison surrendered,” says General Lee), Harper’s Ferry yielded to Jackson.

Fast-riding couriers brought the welcome intelligence of Jackson’s success to General Lee, as the latter was approaching Sharpsburg, and official information speedily came that the result had been the capture of more than eleven thousand men, thirteen thousand small-arms, and seventy-three cannon.  It was probably this large number of men and amount of military stores falling into the hands of the Confederates which afterward induced the opinion that Lee’s sole design in invading Maryland had been the reduction of Harper’s Ferry.

General McClellan had thus failed, in spite of every effort which he had made, to relieve Harper’s Ferry,[1] and no other course remained now but to follow Lee and bring him to battle.  The Federal army accordingly moved on the track of its adversary, and, on the afternoon of the same day (September 15th), found itself in sight of Lee’s forces drawn up on the western side of Antietam Creek, near the village of Sharpsburg.

[Footnote 1:  All along the march he had fired signal-guns to inform the officer in command at Harper’s Ferry of his approach.]

At last the great opponents were in face of each other, and a battle, it was obvious, could not long be delayed.

IV.

THE PRELUDE TO SHARPSBURG.

General Lee had once more sustained a serious check from the skill and soldiership of the officer who had conducted the successful retreat of the Federal army from the Chickahominy to James River.