To that end he began by strengthening his army. He deemed the time now ripe to adopt the plan which he had negatived as premature when Johnston had suggested it. He called to Richmond all the available forces that could be spared from the Southern coasts and elsewhere, swelling his army to 70,000 or 80,000 men. This reinforcement did not indeed give him an army equal to McClellan's in numbers or in equipment, but it materially reduced the disparity between the two opposing forces and opened the way to a hopeful trial of conclusions in the field. But there was, as already stated, a strong Federal force marching by way of Fredericksburg to join McClellan. It numbered more than 40,000 men and was under the very capable command of General McDowell. If that force should form a junction with McClellan the odds against Lee, in spite of reinforcement, would be decisive, and any attempt he might make to save the Confederate capital by offensive defense must fail. Lee's first necessity, therefore, was to prevent McDowell's army of 40,000 men from joining McClellan before Richmond; his second purpose was to bring all his own forces to bear at that crucial point for a supreme effort to overthrow his adversary there. He knew the excessive apprehension felt at the North for the safety of Washington city, and he played upon it with masterly skill. Ever since November, 1861, Stonewall Jackson had been in the Valley of the Shenandoah trying with a totally inadequate force to hold that region and upon occasion to inflict what damage he could upon the foe, especially by destroying a section of the Baltimore and Ohio railroad and of the Chesapeake and Ohio canal, upon which the Federal communications between the forces in West Virginia and the headquarters at Washington depended. Jackson had done some brilliant things in that quarter and had succeeded in detaining there a Federal force much greater than his own, which if set free to join McClellan would have made the Federal army before Richmond irresistible in its strength.