About the 25th, it became evident that the enemy was again advancing upon Maryland and Pennsylvania, and the Sixth Corps, then at Washington,was ordered back to the vicinity of Harper's Ferry. The rebel force moved down the valley,and sent raiding party in to Pennsylvania, which, on the 30th, burned Chambersburg and then retreated, pursued by our cavalry, toward Cumberland. They were met and defeated by General Kelley, and with diminished numbers escaped in to the mountains of West Virginia. From the time of the first raid the telegraph wire were frequently down between Washington and City Point, making it necessary to transmit messages apart of the way by boat. It took from twenty-four to thirty-six hours to get dispatches through and return answers back, so that often orders would be given, and then information would be received showing different state of facts from those on which they were based, causing a confusion and apparent contradiction of orders that must have considerably embarrassed those who had to execute them,and rendered operations against the enemy less effective than they otherwise would have been. To remedy this evil, it was evident to my mind that some person should have the supreme command of all the forces in the Department, and I sore commended.

On the 2nd of August I ordered General Sheridan to report in person to Major-General Halleck, Chief of Staff, at Washington, with a view to his assignment to the command of all the forces against Early. At this time the enemy was concentrated in the neighborhood of Winchester, while our forces, under General Hunter, were concentrated on the Monocacy, at the crossing of the Baltimore and Ohio Railroad, leaving open to the enemy Western Maryland and Southern Pennsylvania. From where I was, I hesitated to give positive orders for the movement of our forcesat Monocacy, lest by so doing I should expose Washington. *Therefore, on the 4th, I left City Point to visit Hunter's command, and determine for myself what was best to be done. On arrival there, and after consultation with General Hunter, I issued to him the following instructions:

MONOCACY BRIDGE, MD., August 5, 1864-8 p.m.

Major General D. HUNTER:

GENERAL: Concentrate all your available force without delay in the vicinity of Harper's Ferry, leaving only such railroad guard sand garrisons for public property as may be necessary. Use, in this concentration, the railroad, if by so doing time can behaved. From Harper's Ferry, if it is found that the enemy had moved north of the Potomac in large force, push north, following him and attacking him wherever found; follow him if driven south of the Potomac as long as it is safe to do so. It if is ascertained that the enemy had but a small force north of the Potomac, then push out with he main force, detaching under 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 no wont he way to join you three other brigades of the best of cavalry, numbering at least 5,000 men and horses. These will be instructed, in the absence of fur the orders, to join you by the south side of the Potomac. One brigade will probably start to-morrow. In pushing up the Shenandoah Valley, where it is expected you will have to go first or last, it is desirable that nothing should be left to invite the enemy to rerun. Take all provisions, forage, and stock wanted for these 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

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*Subordinate reports of operations in the Shenandoah Valley and Maryland up to August 3, 1864, will appear in Vol. XXXVII.

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