Lincoln, in a letter of advice with which he had favoured McClellan a few days previously, had urged the importance of making Lee’s line of supply the first objective of the invading army.  “An advance east of the Blue Ridge,” he said, “would at once menace the enemy’s line of communications, and compel him to keep his forces together; and if Lee, disregarding this menace, were to cut in between the Army of the Potomac and Washington, McClellan would have nothing to do but to attack him in rear.”  He suggested, moreover, that by hard marching it might be possible for McClellan to reach Richmond first.

The Confederate line of communications, so the President believed, ran from Richmond to Culpeper Court House, and McClellan’s advanced guards, on November 7, were within twenty miles of that point.  Lee, however, had altogether failed to respond to Mr. Lincoln’s strategical pronouncements.  Instead of concentrating his forces he had dispersed them; and instead of fearing for his own communications, he had placed Jackson in a position to interfere very seriously with those of his enemy.

Mr. Lincoln’s letter to McClellan shows that the lessons of the war had not been altogether lost upon him.  Generals Banks and Pope, with some stimulus from Stonewall Jackson, had taught him what an important part is played by lines of supply.  He had mastered the strategical truism that an enemy’s communications are his weakest point.  But there were other considerations which had not come home to him.  He had overlooked the possibility that Lee might threaten McClellan’s communications before McClellan could threaten his; and he had yet to learn that an army operating in its own country, if proper forethought be exercised, can establish an alternative line of supply, and provide itself with a double base, thus gaining a freedom of action of which an invader, bound, unless he has command of the sea, to a single line, is generally deprived.

The President appears to have thought that, if Lee were cut off from Richmond, the Army of Northern Virginia would be reduced to starvation, and become absolutely powerless.  It never entered his head that the astute commander of that army had already, in anticipation of the very movement which McClellan was now making, established a second base at Staunton, and that his line of supply, in case of necessity, would not run over the open country between Richmond and Gordonsville, but from Staunton to Culpeper, behind the ramparts of the Blue Ridge.

Lee, in fact, accepted with equanimity the possibility of the Federals intervening between himself and Richmond.  He had already, in the campaign against Pope, extricated himself from such a situation by a bold stroke against his enemy’s communications; and the natural fastness of the Valley, amply provided with food and forage, afforded facilities for such a manoeuvre which had been altogether absent before the Second Manassas.  Nor was he of Mr. Lincoln’s opinion, that if