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.
The section that received my closest attention has its northern limit along the Potomac between McCoy's ferry at the eastern base of the North Mountain, and Harper's Ferry at the western base of the Blue Ridge. The southern limit is south of Staunton, on the divide which separates the waters flowing into the Potomac from those that run to the James. The western boundary is the eastern slope of the Alleghany Mountains, the eastern, the Blue Ridge; these two distinct mountain ranges trending about southwest inclose a stretch of quite open, undulating country varying in width from the northern to the southern extremity, and dotted at frequent intervals with patches of heavy woods: At Martinsburg the valley is about sixty miles broad, and on an east and west line drawn through Winchester about forty-five, while at Strasburg it narrows down to about twenty-five. Just southeast of Strasburg, which is nearly midway between the eastern and western walls of the valley, rises an abrupt range of mountains called Massanutten, consisting of several ridges which extend southward between the North and South Forks of the Shenandoah River until, losing their identity, they merge into lower but broken ground between New Market and Harrisonburg. The Massanutten ranges, with their spurs and hills, divide the Shenandoah Valley into two valleys, the one next the Blue Ridge being called the Luray, while that next the North Mountain retains the name of Shenandoah.
A broad macadamized road, leading south from Williamsport, Maryland, to Lexington, Virginia, was built at an early day to connect the interior of the latter State with the Chesapeake and Ohio canal, and along this road are situated the principal towns and villages of the Shenandoah Valley, with lateral lines of communication extending to the mountain ranges on the east and west. The roads running toward the Blue Ridge are nearly all macadamized, and the principal ones lead to the railroad system of eastern Virginia through Snicker's, Ashby's Manassas, Chester, Thornton's Swift Run, Brown's and Rock-fish gaps, tending to an ultimate centre at Richmond. These gaps are low and easy, offering little obstruction to the march of an army coming from eastern Virginia, and thus the Union troops operating west of the Blue Ridge were always subjected to the perils of a flank attack; for the Confederates could readily be brought by rail to Gordonsville and Charlottesville, from which points they could move with such celerity through the Blue Ridge that, on more than one occasion, the Shenandoah Valley had been the theatre of Confederate success, due greatly to the advantage of possessing these interior lines.
Nature had been very kind to the valley, making it rich and productive to an exceptional degree, and though for three years contending armies had been marching up and down it, the fertile soil still yielded ample subsistence for Early's men, with a large surplus for the army of Lee. The ground had long been well cleared of timber, and the rolling surface presented so few obstacles to the movement of armies that they could march over the country in any direction almost as well as on the roads, the creeks and rivers being everywhere fordable, with little or no difficulty beyond that of leveling the approaches.