To that end, first of all, he had strengthened the army at Richmond by calling to it every man that could be spared from coast defense and from the regions farther south. Next he had set Jackson at work in the Valley, to occupy the forces there and in West Virginia, and by threatening Washington to divert from McClellan's reinforcement an additional army of 40,000 men which had been intended to strengthen him into irresistibility.
When Jackson, beset by four armies, had escaped from two of them and had defeated the other two, Lee sent strong reinforcements to him in a conspicuous way, so that he might seem about to advance down the Valley, cross the Potomac and in strong force occupy the region north of the Potomac and threaten the capture of Washington itself.
By this strategy Lee had managed to detain 65,000 Federals in the Valley, and 20,000 or 30,000 more in and around Washington, whose fighting force must otherwise have been added to McClellan's already superior army before Richmond. Then he had managed to have Jackson suddenly and secretly quit the Valley, with the force that had there achieved such spectacular results, together with the troops that had been ostensibly sent to reinforce him for an aggressive campaign and by a rapid movement to join the army at Richmond and assist it in a supreme endeavor to dislodge McClellan.
The situation then was this: Relying upon a reinforcement of 40,000 men under McDowell, McClellan had dangerously divided his army, keeping about half of it north and about half of it south of the Chickahominy river. His desire was to press forward his siege operations on the east of the Confederate capital and at the same time to maintain a threatening force north of the city. It was his purpose so soon as McDowell should add his 40,000 men to this army on the north, to sweep forward with the combined forces and irresistibly to push a conquering column into Richmond.
But Lee had baffled all these plans by his masterful strategy. He had compelled the diversion of McDowell to the Valley, and while the authorities at Washington were nervously expecting Jackson to swoop down upon that city, Jackson with his whole force, which had slipped out of the Valley, suddenly appeared at Ashland, about a dozen miles northwest of Richmond and immediately upon McClellan's right flank.
In the meanwhile Lee had sent Stuart—perhaps the most daring and enterprising of the Southern cavalry leaders—with a body of 1,200 or 1,500 horsemen and two guns, to the rear of McClellan's position, there to find out the disposition of troops, the condition of the roads and bridges, and whatever else might open the way to that gigantic operation of offensive defense which Lee intended presently to undertake.
Stuart moved promptly into McClellan's rear and swept around it like a whirlwind. Finding that a tardy resistance was taking the form of an organized effort to cut off his retreat by the route over which he had come, the gaily enterprising cavalier of the South, instead of turning back and trying to retrace his steps as his enemy expected him to do, decided to ride on all the way around McClellan's army and thus spectacularly to emphasize the imperfection of McClellan's precaution for the protection of that rear which Lee was planning presently to assail tempestuously. He rode completely around McClellan, crossing his line of communications, rebuilding a bridge which had been destroyed for the purpose of cutting him off and entrapping him, and returning to Richmond with a loss so small as to be scarcely worthy of mention in an official report.
This raid was made on the twelfth and thirteenth of June, and equipped with the detailed information secured by it Lee planned to assail McClellan on the twenty-sixth of June with a force sufficient to dislodge him from his besieging positions, to break his line of communication and supply by way of the White House on the York river, and to compel his retreat from the front of the Confederate capital to some point on the James river, where his gunboats could afford him needed protection.
For the purposes of this operation Lee had a force somewhat inferior in men and guns to McClellan's, but not greatly inferior. On the other hand McClellan's army was badly placed, with half of it on the north and half of it on the south of the Chickahominy, neither half being within easy supporting distance of the other, while the line of communication and supply by way of the White House was peculiarly vulnerable in case of an attack from the rear.
Reckoning upon these advantages, it was Lee's plan to have Jackson move down from Ashland, assail McClellan's right wing in flank and rear, drive back his forces and thus open the crossings of the river to the other Confederate corps, which were to cross one after the other and assail the enemy in front while Jackson should attack him in rear and flank.