[Footnote 1: The reader will perceive that the intent to invade Pennsylvania is repeatedly attributed in these pages to General Lee. His own expression is, "by threatening Pennsylvania, to induce the enemy," etc. That he designed invasion, aided by the recruits anticipated in Maryland, seems unquestionable; since, even after discovering the lukewarmness of the people there by the fact that few joined his standard, he still advanced to Hagerstown, but a step from the Pennsylvania line. These facts have induced the present writer to attribute the design of actual invasion to Lee with entire confidence; and all the circumstances seem to him to support that hypothesis.]

The promises of his address had been kept. No one had been forced to follow the Southern flag; and now, when the people turned their backs upon it, closing the doors of the houses in the faces of the Southern troops, they remained unmolested. Lee had thus given a practical proof of the sincerity of his character. He had promised nothing which he had not performed; and in Maryland, as afterward in Pennsylvania, in 1863, he remained firm against the temptation to adopt the harsh course generally pursued by the commanders of invading armies. He seems to have proceeded on the principle that good faith is as essential in public affairs as in private, and to have resolved that, in any event, whether of victory or disaster, his enemies should not have it in their power to say that he broke his plighted word, or acted in a manner unbecoming a Christian gentleman.

Prompt action was now necessary. The remnants of General Pope's army, greatly scattered and disorganized by the severe battle of Manassas, had been rapidly reformed and brought into order again, and to this force was added a large number of new troops, hurried forward from the Northern States to Washington. This new army was not to be commanded by General Pope, who had been weighed and found wanting in ability to contend with Lee. The force was intrusted to General McClellan, in spite of his unpopularity with the Federal authorities; and the urgent manner in which he had been called upon to take the head of affairs and protect the Federal capital, is the most eloquent of all commentaries upon the position which he held in the eyes of the country and the army. It was felt, indeed, by all that the Federal ship was rolling in the storm, and an experienced pilot was necessary for her guidance. General McClellan was accordingly directed, after General Pope's defeat, to take command of every thing, and see to the safety of Washington; and, finding himself at length at the head of an army of about one hundred thousand men, he proceeded, after the manner of a good soldier, to protect the Federal capital by advancing into upper Maryland in pursuit of Lee.

III.

MOVEMENTS OF THE TWO ARMIES.

General Lee was already moving to the accomplishment of his designs, the capture of Harper's Ferry, and an advance into the Cumberland Valley.

His plan to attain the first-mentioned object was simple, and promised to be successful. Jackson was to march around by way of "Williamsport and Martinsburg," and thus approach from the south. A force was meanwhile to seize upon and occupy the Maryland Heights, a lofty spot of the mountain across the Potomac, north of the Ferry. In like manner, another body of troops was to cross the Potomac, east of the Blue Ridge, and occupy the Loudon Heights, looking down upon Harper's Ferry from the east. By this arrangement the retreat of the enemy would be completely cut off in every direction. Harper's Ferry must be captured, and, having effected that result, the whole Confederate force, detached for the purpose, was to follow the main body of this army in the direction of Hagerstown, to take part in the proposed invasion of Pennsylvania.

This excellent plan failed, as will be seen, from no fault of the great soldier who devised it, but in consequence of unforeseen obstacles, and especially of one of those singular incidents which occasionally reverse the best-laid schemes and abruptly turn aside the currents of history.

Jackson and the commanders coöperating with him moved on September 10th. General Lee then with his main body crossed the South Mountain, taking the direction of Hagerstown. Meanwhile, General McClellan had advanced cautiously and slowly, withheld by incessant dispatches from Washington, warning him not to move in such a manner as to expose that city to danger. Such danger existed only in the imaginations of the authorities, as the army in advancing extended its front from the Potomac to the Baltimore and Ohio Railroad. General McClellan, nevertheless, moved with very great precaution, feeling his way, step by step, like a man in the dark, when on reaching Frederick City, which the Confederates had just evacuated, good fortune suddenly came to his assistance. This good fortune was the discovery of a copy of General Lee's orders of march for the army, in which his whole plan was revealed. General McClellan had therein the unmistakable evidence of his opponent's intentions, and from that moment his advance was as rapid as before it had been deliberate.

The result of this fortunate discovery was speedily seen. General Lee, while moving steadily toward Hagerstown, was suddenly compelled to turn his attention to the mountain-passes in his rear. It had not been the intention of Lee to oppose the passage of the enemy through the South Mountain, as he desired to draw General McClellan as far as possible from his base, but the delay in the fall of Harper's Ferry now made this necessary. It was essential to defend the mountain-defiles in order to insure the safety of the Confederate troops at Harper's Ferry; and Lee accordingly directed General D.H. Hill to oppose the passage of the enemy at Boonsboro Gap, and Longstreet was sent from Hagerstown to support him.