Edward Alfred Pollard, The lost cause; a new Southern history of the War of the Confederates ... Drawn from official sources and approved by the most distinguished Confederate leaders.

A copy of the order directing the movement of ;he army from Frederick had been sent to D. H. Hill; and this vain and petulant officer, in a moment of passion, had thrown the paper on the ground. It was picked up by a Federal soldier, and McClellan thus strangely became possessed of the exact detail of his adversary's plan of operations.

His first thought was to relieve Harper's Ferry. He immediately began to push forward rapidly, and on the afternoon of the 13th was reported approaching the pass in South Mountain on the Boonesboroa and Frederick road. By penetrating the mountains at this point, he would reach the rear of McLaws, and be enabled to relieve the garrison at Harper's Ferry. To prevent this, Gen. D. H. Hill was directed to guard the Boonesboroa Gap, and Longstreet ordered to march from Hagerstown to his support.

The small command of Gen. Hill repelled the repeated assaults of the Federal army, and held it in check for five hours. Several attacks on the centre were gallantly repulsed by Colquitt's brigade, and Rodes, on the left, maintained his position against heavy odds with the utmost tenacity. Longstreet, leaving one brigade at Hagerstown, had hurried to the assistance of Hill, and reached the scene of action between three and four P. M. His troops, much exhausted by a long, rapid march and the heat of the day, were disposed on both sides of the turnpike. The battle continued with great animation until night. On the south of the turnpike, the enemy was driven back some distance, and his attack on the centre repulsed with loss. His great superiourity of numbers enabled him to extend beyond both of the Confederate flanks. By this means he succeeded in reaching the summit of the mountain, beyond our left, and pressing heavily from that direction, gradually forced our troops back, after an obstinate resistance. Darkness put an end to the contest. The effort to force the passage of the mountains had failed, but it was manifest that, without reinforcements, we could not hazard a renewal of the engagement, as the enemy could easily turn either flank. Information was also received that another large body of Federal troops had, during the afternoon, forced their way through Crampton's Gap, only five miles in rear of McLaws. Under these circumstances, it was determined by Gen. Lee to retire to Sharpsburg, where he would be upon the flank and rear of the enemy, should he move against McLaws, and where he could more readily unite with the rest of the army.

The resistance that had been offered to the enemy at Boonesboroa, secured sufficient time to enable Gen. Jackson to complete the reduction of Harper's Ferry. On the afternoon of the 14th, when he found that the troops of Walker and McLaws were in position to cooperate in the attack he ordered Gen. A. P. Hill to turn the enemy's left flank, and enter Harper's Ferry. Gen. A. P. Hill observing a hill on the enemy's extreme left