The Confederates were the first to realize that this was an error. However desirable it might be to hold Harper's Ferry as the key to the Baltimore and Ohio, and to Maryland, General Johnston quickly discovered that, while it was secure enough against an attack in front, across the Potomac, it was an easy capture for a superior force that should cross the river above or below it, and attack it from the Virginia side. For its defence, his force of six thousand five hundred men would not suffice against Patterson's twenty thousand, and he requested permission to withdraw to Winchester, twenty miles to the southwest. This suggestion was most unpalatable to the Confederate authorities, who understood well that the popular interpretation of the movement would be detrimental to the cause. But the fear that McClellan would join Patterson from West Virginia, and that the loss of an army of six thousand five hundred would be even more depressing than a retreat, they reluctantly consented to Johnston's plan. He destroyed everything at Harper's Ferry that could be destroyed, on June 13th and 14th; and when Patterson, after repeated promptings from Washington, arrived there on the 15th, he found no determined enemy and no mighty battle awaiting him, but only the barren victory of an unopposed occupation of a ruined and deserted camp. [Illustration: A RAILROAD BATTERY.] CHAPTER V. ARMY ORGANIZATION NORTH AND SOUTH. CONFEDERATE ADVANTAGES--THE LEADING GENERAL OFFICERS--GRADUATES OF WEST POINT JOIN THE CONFEDERACY--CAPITAL REMOVED FROM MONTGOMERY--PRESIDENT LINCOLN'S CALL FOR SOLDIERS AND SAILORS--SOUTHERN PRIVATEERS--"ON TO RICHMOND!" Although up to this time no important engagements between the troops had taken place, the war was actually begun. The Sumter affair had been the signal for both sides to throw away subterfuge and disguise, and it became thenceforth an open struggle for military advantage. The South no longer pleaded State rights, but military necessity, for seizing such Government posts and property as were within reach; the North no longer acted under the restraint of hesitation to commit an open breach, for the peace was broken irrevocably, and whatever it was possible to do, in the way of defence or offence, was now become politic. The two contending powers were entering on the struggle under very different conditions and with unequal advantages. Before taking up the military operations which ensued, it will be interesting to look at these conditions.