But Lee had not destroyed McClellan's army, or captured it, or even weakened it in any conspicuous degree. That army, splendidly organized, superbly equipped, and strengthened rather than weakened in morale, lay securely at rest on the James river, within easy striking distance of Richmond. There was no knowing at what moment McClellan might hurl it again upon Richmond or upon that commanding key to Richmond--the Petersburg position. In the hands of a capable commander McClellan's army would at this time have been a more serious menace than ever to the Confederate capital, for it now had an absolutely secure and unassailable base of operations, while its fighting quality had been improved rather than impaired by its seven days of battling. Thus the second part of Lee's military problem remained still to be solved, and it was very greatly the more difficult part--the part that most imperatively called for the exercise of strategic genius of a high order. He must prevent a junction between Pope's army, which was now advancing by way of Manassas Junction, and McClellan's force on the James river. He must overthrow Pope on the one hand and compel McClellan to retire on the other. For the accomplishment of this Lee relied confidently upon the positively morbid dread of the loss of Washington which at that time filled the Northern mind and inspired every order given at the Federal capital. His problem was to put Washington in peril without losing Richmond, and thus to compel the withdrawal of McClellan's army for the defense of the Federal capital and to meet a threatened invasion of the North. To that end Lee boldly risked a division of his force as he afterwards did on several occasions in presence of an enemy who already outnumbered him. On the thirteenth of July he detached Jackson, with his own and Ewell's commands, to operate against Pope in northern Virginia, himself holding Richmond with the rather scant remainder of his army. Jackson moved at once to Orange Court House, confronting Pope. This movement threatened Washington only in a rather remote way and not very seriously, but it had the desired effect. A part of McClellan's force was at once withdrawn from the position at Harrison's Landing and sent by water to the national capital as a reserve and reinforcement for Pope in case that general should be beaten in the field. Promptly--near the end of July--Lee sent A. P. Hill's corps to Jackson, and, thus strengthened, Jackson pushed his column across the Rapidan river and encountered a part of Pope's forces at Cedar Mountain on the ninth of August. The action was not a decisive one, but it served Lee's purpose of compelling the early and complete withdrawal of McClellan from his threatening position below Richmond.