In the meantime Ewell crossed the Potomac on the 15th, with two of his divisions and proceeded to Hagerstown, Maryland, while Jenkins's brigade of cavalry was sent to Chambersburg, to scour the country and gather in supplies.
These movements of the Confederates greatly mystified Hooker; it was of the greatest consequence to him to know whether they portended simply a reconnaissance and cavalry raid, or whether they were the prelude to another invasion. He could not afford to follow Ewell, and throw his army across the river, leaving Washington exposed from the South side, and Lee's whereabouts, and whether he might not be sending reinforcements to the Western army remained a great perplexity.
On the other hand, General Lee expresses himself in doubt, when Hooker swung his right wing towards the waters of the Upper Potomac, whether his purpose was to occupy Harper's Ferry, or whether he meditated crossing the mountains and pushing into the valley.
While it was part of Lee's plan to get Hooker out of Virginia, he had no wish to hurry him at this juncture. On the 10th he wrote to Ewell, "Longstreet's corps has been operating with a view to embarrass the enemy as to our movements, so as to detain his forces east of the Mountains, until A. P. Hill could get up to your support; should the enemy force a passage, you would be separated, which it is the object of Longstreet to prevent if possible. * * * I very much regret that you have not the benefit of your whole corps, for with that north of the Potomac, should we be able to detain Hooker's army from following you, you would be able to accomplish as much unmolested, as the whole army could 'per form with General Hooker in its front. Not knowing what force there is at Harper's Ferry, or could be collected to oppose your progress, I cannot give you definite instructions, especially as the movements of General Hooker's army are not yet ascertained."
Hooker now had his army posted to cover all the approaches to Washington from the Orange and Alexandria Railroad, his right resting about Fairfax Station, and his left at Warrenton, about thirty-five miles distant. Such being the position of the two armies, a most important duty was devolved on the respective
