"Use in this concentration the railroad, if by so doing time can be saved. From Harper's Ferry, if it is found that the enemy has moved north of the Potomac in large force, push north, following and attacking him wherever found; following him, if driven south of the Potomac, as long as it is safe to do so. If it is ascertained that the enemy has but a small force north of the Potomac, then push south the main force, detaching, under a competent commander, a sufficient force to look after the raiders and drive them to their homes. In detaching such a force, the brigade of cavalry now en route from Washington via Rockville may be taken into account.
"There are now on the way to join you three other brigades of the best of cavalry, numbering at least five thousand men and horses.
These will be instructed, in the absence of further orders, to join you by the south side of the Potomac. One brigade will probably start to-morrow.
"In pushing up the Shenandoah Valley, as it is expected you will have to go first or last, it is desirable that nothing should be left to invite the enemy to return. Take all provisions, forage, and stock wanted for the use of your command. Such as cannot be consumed, destroy. It is not desirable that the buildings should be destroyed--they should, rather, be protected; but the people should be informed that so long as an army can subsist among them recurrences of these raids must be expected, and we are determined to stop them at all hazards.
"Bear in mind, the object is to drive the enemy south; and to do this you want to keep him always in sight. Be guided in your course by the course he takes.
"Make your own arrangements for supplies of all kinds, giving regular vouchers for such as may be taken from loyal citizens in the country through which you march.
"Very respectfully, "U. S. GRANT, Lieut.-General."
"Major-General D. HUNTER, "Commanding Department of West Virginia."
When I had read the letter addressed to Hunter, General Grant said I would be expected to report directly to him, as Hunter had asked that day to be wholly relieved, not from any chagrin at my assignment to the control of the active forces of his command, but because he thought that his fitness for the position he was filling was distrusted by General Halleck, and he had no wish to cause embarrassment by remaining where he could but remove me one degree from the headquarters of the army. The next day Hunter's unselfish request was complied with, and an order was issued by the President, consolidating the Middle Department, the Department of Washington, the Department of the Susquehanna, and the Department of West Virginia.
Under this order these four geographical districts constituted the Middle Military Division, and I was temporarily assigned to command it. Hunter's men had been bivouacking for some days past in the vicinity of Monocacy Junction and Frederick, but before General Grant's instructions were written out, Hunter had conformed to them by directing the concentration at Halltown, about four miles in front of Harper's Ferry, of all his force available for field service.
Therefore the different bodies of troops, with the exception of Averell's cavalry, which had followed McCausland toward Moorefield after the burning of Chambersburg, were all in motion toward Halltown on August 6.
Affairs at Monocacy kept me but an hour or two, and these disposed of, I continued on to Harper's Ferry by the special train which had brought me from Washington, that point being intended as my headquarters while making preparations to advance. The enemy was occupying Martinsburg, Williamsport, and Shepherdstown at the time; sending occasional raiding parties into Maryland as far as Hagerstown. The concentration of my troops at Halltown being an indication to Early that we intended to renew the offensive, however, he immediately began counter preparations by drawing in all his detached columns from the north side of the Potomac, abandoning a contemplated raid into Maryland, which his success against Crook at Kernstown had prompted him to project, and otherwise disposing himself for defense.
At Harper's Ferry I made my headquarters in the second story of a small and very dilapidated hotel, and as soon as settled sent for Lieutenant John R. Meigs, the chief engineer officer of the command, to study with him the maps of my geographical division. It always came rather easy to me to learn the geography of a new section, and its important topographical features as well; therefore I found that, with the aid of Meigs, who was most intelligent in his profession, the region in which I was to operate would soon be well fixed in my mind. Meigs was familiar with every important road and stream, and with all points worthy of note west of the Blue Ridge, and was particularly well equipped with knowledge regarding the Shenandoah Valley, even down to the farmhouses. He imparted with great readiness what he knew of this, clearly pointing out its configuration and indicating the strongest points for Confederate defense, at the same time illustrating scientifically and forcibly the peculiar disadvantages under which the Union army had hitherto labored.
