But Lee knew how almost insanely the administration at Washington dreaded every threat against that city or the country north of it, and he had successfully counted upon that absurd nervousness to enable Jackson, with 16,000 or 17,000 men, to neutralize McDowell's army of 40,000 in the great game then being played for the possession of Richmond. He had made a zero of Fremont and Schenck in the problem. He had converted Banks's army into a Potomac river-picket guard, and he had compelled McDowell's 40,000 men to remain inactive as a garrison defending Washington. Never in all the war was so small a force as Jackson's made to neutralize so large a force. By the simple virtue of Lee's masterful strategy and Jackson's extraordinary capacity in execution, 17,000 men occupied 65,000 and kept them completely out of the decisive struggle. And as if to add emphasis to the situation, the 17,000 who had thus paralyzed three or four times their number, were themselves brought upon the field before Richmond in time to play their full part in the critical and decisive actions from which their previous activity had excluded so great a number of their opponents. But the story of the Valley campaign is not yet fully told. Having driven Fremont back into West Virginia and Banks beyond the Potomac at Williamsport, Jackson was ordered by Lee to make a demonstration threatening an invasion of Maryland and seeming to threaten an assault upon Washington, by way of still further disarranging the Federal plans and diverting Federal forces from the assault upon Richmond. Jackson moved at once upon Harper's Ferry and for a time seemed not only determined but quite easily able to cross the Potomac there and push forward into Maryland and Pennsylvania or to sweep with enthusiastic fury upon Washington itself.