The defeat of General Pope opened the way for movements not contemplated, probably, by General Lee, when he marched from Richmond to check the advance in Culpepper. His object at that time was doubtless simply to arrest the forward movement of the new force threatening Gordonsville. Now, however, the position of the pieces on the great chess-board of war had suddenly changed, and it was obviously Lee's policy to extract all the advantage possible from the new condition of things.

He accordingly determined to advance into Maryland—the fortifications in front of Washington, and the interposition of the Potomac, a broad stream easily defended, rendering a movement in that direction unpromising. On the 3d of September, therefore, and without waiting to rest his army, which was greatly fatigued with the nearly continuous marching and fighting since it had left the Rapidan, General Lee moved toward Leesburg, crossed his forces near that place, and to the music of the bands playing the popular air, "Maryland, my Maryland," advanced to Frederick City, which he occupied on the 7th of September.

Lee's object in invading Maryland has been the subject of much discussion, one party holding the view that his sole aim was to surround and capture a force of nine or ten thousand Federal troops stationed at Harper's Ferry; and another party maintaining that he proposed an invasion of Pennsylvania as far as the Susquehanna, intending to fight a decisive battle there, and advance thereafter upon Philadelphia, Baltimore, or Washington. The course pursued by an army commander is largely shaped by the progress of events. It can only be said that General Lee, doubtless, left the future to decide his ultimate movements; meanwhile he had a distinct and clearly-defined aim, which he states in plain words.

His object was to draw the Federal forces out of Virginia first. The movement culminating in the victory over the enemy at Manassas had produced the effect of paralyzing them in every quarter. On the coast of North Carolina, in Western Virginia, and in the Shenandoah Valley, had been heard the echo of the great events in Middle and Northern Virginia. General Burnside's force had been brought up from the South, leaving affairs at a stand-still in that direction; and, contemporaneously with the retreat of General Pope, the Federal forces at Washington and beyond had fallen back to the Potomac. This left the way open, and Lee's farther advance, it was obvious, would now completely clear Virginia of her invaders. The situation of affairs, and the expected results, are clearly stated by General Lee:

"The war was thus transferred," he says, "from the interior to the frontier, and the supplies of rich and productive districts made accessible to our army. To prolong a state of affairs in every way desirable, and not to permit the season for active operations to pass without endeavoring to inflict other injury upon the enemy, the best course appeared to be the transfer of the army into Maryland."

The state of things in Maryland was another important consideration. That great Commonwealth was known to be sectionally divided in its sentiment toward the Federal Government, the eastern portion adhering generally to the side of the South, and the western portion generally to the Federal side. But, even as high up as Frederick, it was hoped that the Southern cause would find adherents and volunteers to march under the Confederate banner. If this portion of the population had only the opportunity to choose their part, unterrified by Federal bayonets, it was supposed they would decide for the South. In any event, the movement would be important. The condition of affairs in Maryland, General Lee says, "encouraged the belief that the presence of our army, however inferior to that of the enemy, would induce the Washington Government to retain all its available force to provide for contingencies which its course toward the people of that State gave it reason to apprehend," and to cross the Potomac "might afford us an opportunity to aid the citizens of Maryland in any efforts they might be disposed to make to recover their liberty."

It may be said, in summing up on this point, that Lee expected volunteers to enroll themselves under his standard, tempted to do so by the hope of throwing off the yoke of the Federal Government, and the army certainly shared this expectation. The identity of sentiment generally between the people of the States of Maryland and Virginia, and their strong social ties in the past, rendered this anticipation reasonable, and the feeling of the country at the result afterward was extremely bitter.

Such were the first designs of Lee; his ultimate aim seems as clear. By advancing into Maryland and threatening Baltimore and Washington, he knew that he would force the enemy to withdraw all their troops from the south bank of the Potomac, where they menaced the Confederate communications with Richmond; when this was accomplished, as it clearly would be, his design was, to cross the Maryland extension of the Blue Ridge, called there the South Mountain, advance by way of Hagerstown into the Cumberland Valley, and, by thus forcing the enemy to follow him, draw them to a distance from their base of supplies, while his own communications would remain open by way of the Shenandoah Valley. This was essentially the same plan pursued in the campaign of 1863, which terminated in the battle of Gettysburg. General Lee's movements now indicated similar intentions. He doubtless wished, in the first place, to compel the enemy to pursue him—then to lead them as far as was prudent—and then, if circumstances were favorable, bring them to decisive battle, success in which promised to open for him the gates of Washington or Baltimore, and end the war.

It will now be seen how the delay caused by the movement of Jackson against Harper's Ferry, and the discovery by General McClellan of the entire arrangement devised by Lee for that purpose, caused the failure of this whole ulterior design.

[Illustration: Map—Map of the MARYLAND CAMPAIGN.]