In the course of this advance, Lee made one capital blunder. It was his courteous custom, in giving orders to his higher lieutenants, to leave much to their discretion, if only by way of emphasizing his confidence in them. In this case he left much to the discretion of Stuart, who had no discretion, although he had every other good quality of the soldier. Lee ordered Stuart to make certain movements if they commended themselves to his judgment, but left him in effect free to do as he pleased, assuming that he would please to do that which was discreet, bearing in mind that the cavalry are the eyes and ears of the army.
It was Stuart's chief business to find out and report every movement of the Army of the Potomac, to follow its every march, to learn what it was planning to do, and at every step to find out and report to Lee the force employed in each maneuver. Stuart was an adept in this work. No man then living—probably no man who ever lived—knew better than he did how to find out the purposes of an enemy or to estimate his strength or to determine where and when that enemy meant to strike.
But by virtue of his orders, Stuart was free to do what he pleased; and it pleased him to find out how nearly his cavaliers could ride into Washington, to throw shells into that city and generally to impress himself dramatically and theatrically upon the Federal administration as a terror.
As a consequence Lee was left without that information as to his adversary's movements which he depended upon the cavalry to furnish. While Stuart was trying to throw shells into Washington, Meade was concentrating his forces toward Gettysburg, to meet his opponent there and Lee was left in ignorance of the fact.
Accordingly when the head of Lee's somewhat scattered and straggling column came upon a Federal force occupying a strong position at Gettysburg which it had been Lee's intention that his own advance forces should seize and hold, there were all the elements of surprise in the situation.
Neither army was as yet sufficiently concentrated to deliver a blow that might be decisive. Lee had in all about 73,500 infantry and artillery—the largest army he ever commanded. Meade had about 82,000 effective infantry and artillery. The cavalry on each side numbered ten or eleven thousand sabers, but Lee's horsemen were absent, trying to make a display of themselves, while Meade's were in front, where they ought to have been, trying to secure for their commander full information and promptly to seize upon the best positions that might avail to give him advantage in the approaching fight. This difference gave to Meade about 93,000 fighting men against 73,000 on the other side.
Lee's army was strangely scattered. A part of it was at York; a part of it at Carlisle; a part of it at Chambersburg, and another part in front of Gettysburg. Because of Stuart's aberration Lee knew nothing of his enemy's movements until the head of his column ran against Meade's forces at Gettysburg. He seems to have expected Meade to remain south of the Potomac, or at the most to cross that river and place himself in the northern defenses of Washington. He had ordered the concentration of the Confederate forces at Gettysburg without the smallest expectation of finding the Army of the Potomac there to meet him in full force.
A glance at a map will show the reader how completely the position at Gettysburg dominates the military geography, and how perfectly his mastery of it would have enabled Lee to dictate the further course of the campaign.
It is greatly to the credit of General Meade as a strategist that he quickly saw all this and hurried his army forward to occupy that commanding position before Lee could seize upon and control it.
He did this masterfully. When Lee's advance reached Gettysburg on the first of July, it found itself opposed by a force too great for it to deal with in any summary fashion. And that force had seized upon positions of the utmost strategic value before the Confederates reached Gettysburg.