The arrival of General Sumner, however, completely changed the face of affairs, and, as his fresh troops advanced, those which had been so roughly handled by Jackson had an opportunity to reform.  This was rapidly effected, and, having marshalled his troops, General Sumner, an officer of great dash and courage, made a vigorous charge.  From this moment the battle began to rage with new fury.  General Lee had sent to the left the brigades of Colquitt, Ripley, and McRae, and with these, the troops of Hood, and his own shattered division, Jackson presented a stubborn front, but his loss was heavy.  General Starke, of the Old Division, was killed; the brigade, regimental, and company officers fell almost without an exception, and the brigades dwindled to mere handfuls.

Under the great pressure, Jackson was at length forced back.  One of General Sumner’s divisions drove the right of the Confederates beyond the Hagerstown road, and, at this moment the long struggle seemed ended; the great wrestle in which the adversaries had so long staggered to and fro, advancing and retreating in turn, seemed at last virtually decided in favor of the Federal arms.

This was undoubtedly the turning-point of the battle of Sharpsburg, and General Lee had witnessed the conflict upon his left with great anxiety.  It was impossible, however, to send thither more troops than he had already sent.  As will be seen in a moment, both his centre and right were extremely weak.  A.P.  Hill and General McLaws had not arrived from Harper’s Ferry.  Thus the left had been reenforced to the full extent of Lee’s ability, and now that portion of his line seemed about to be crushed.

Fortunately, however, General McLaws, who had been delayed longer than was expected by General Lee, at last arrived, and was hurried to the left.  It was ten o’clock, and in that one hour the fighting of an entire day seemed to have been concentrated.  Jackson was holding his ground with difficulty when the divisions of McLaws and Walker were sent to him.  As soon as they reached the field, they were thrown into action, and General Lee had the satisfaction of witnessing a new order of things.  The advance—­it might rather be called the onward rush—­of the Federal line was checked.  Jackson’s weary men took fresh heart; that great commander promptly assumed the offensive, and, advancing his whole line, drove the enemy before him until he reoccupied the ground from which General Sumner had forced him to retire.

From the ground thus occupied, the Federal forces were unable to dislodge him, and the great struggle of “the left at Sharpsburg” was over.  It had begun at dawn and was decided by ten or eleven o’clock, and the troops on both sides had fought as resolutely as in any other action of the war.  The event had been decided by the pertinacity of the Southern troops, and by the prompt movement of reenforcements by General Lee from his right and centre.  Posted near his centre, he had surveyed at one glance the whole field of action; the design of General McClellan to direct his main assault upon the Confederate left was promptly penetrated, and the rapid concentration of the Southern forces in that quarter had, by defeating this movement, decided the result of the battle.