Hooker, under orders, retired toward Washington, leaving Lee free to add Hill's corps to the forces with which he was advancing northward.
Ewell swept down the valley and assailed Winchester, where he completely broke and destroyed Milroy's force of ten thousand men, capturing four thousand of them and driving the rest into disorderly retreat upon Harper's Ferry.
Lee promptly threw Hill's corps into the Shenandoah Valley, while Longstreet moved northward upon parallel lines, east of the mountains.
Presently the Confederate cavalry crossed the Potomac and reached Chambersburg in Pennsylvania. The infantry and artillery promptly followed, and by the twenty-second or twenty-third of June, the whole Confederate army was in Pennsylvania—threatening Washington, threatening Baltimore, threatening Philadelphia, and gravely menacing even New York.
A great panic ensued among the Northern people, to whom the fact of war had not often before been brought home in this intimate and terrifying fashion. Women and children fled as refugees. Horses and cattle were driven away into hiding. Silverware and jewels were hastily buried, and all food stuffs that could be carried away were hidden. For the first time the people at the North had some small realization of what war means to those who dwell in an invaded country. They suffered no such desolation as that which for years overspread northern Virginia. They learned no such lesson of havoc as that which Sheridan afterwards mercilessly taught the people of that fruitful valley of Virginia over which, after his desolating march, he picturesquely said that "the crow that flies must carry his rations with him." But at the least they learned that to a people whose land is invaded, war is truly "all hell," in General Sherman's phrase.
There was a hurried calling out of militia in the threatened states, quite as if militia could be expected to stand against the veterans who had fought at Richmond, at Antietam, at Fredericksburg and at Chancellorsville. Half a million of militia, if so many could have been brought together, would have been able to oppose no obstacle to the determined will of such veteran soldiers as these. At that stage of the war, the militia and raw, untrained volunteers on either side, had ceased to be regarded as forces to be reckoned with.
A more important fact was that Hooker was moving with his veteran army to meet Lee, keeping himself always between the great Confederate and the National capital.
Again as during the former invasion, there were eleven thousand Federal troops holding Harper's Ferry. Again, as a year before, the general commanding the Army of the Potomac wanted to save them to his army by ordering them to evacuate the place and join him in the field. Again, as on the former occasion, Halleck refused to sanction this, in spite of the obvious fact that the Confederates must certainly and easily capture the whole of that force unless it should save itself by timely retreat.
About this time Hooker, in disgust at the restraints to which he was subjected, asked to be relieved of the command of the Army of the Potomac, and General Meade, a very much abler man, was appointed to succeed him. Meade instantly ordered the evacuation of Harper's Ferry—the very thing that Hooker had been forbidden to order, and thus saved eleven thousand seasoned troops to the Army with which he must presently confront Lee.
On the twenty-eighth of June Lee's army lay at Chambersburg, York, and Carlisle, in Pennsylvania. In that position it threatened Baltimore, Harrisburg and Philadelphia about equally. It might move upon either at will and in either case cut off Washington. The problem of the Army of the Potomac was to find out its adversary's intention and interpose itself at whatever point interposition might seem to be most necessary.