I am directed by the major-general commanding to inform you that you will march at seven o'clock A.M., on the 13th inst., with all your available force, except one brigade, for the purpose of turning the enemy's position on his left, and of throwing your command between him and Richmond, isolating him from his supplies, checking his retreat, and inflicting on him every possible injury which will tend to his discomfiture and defeat. To accomplish this, the general suggests that you ascend the Rappahannock by the different routes, keeping well out of the view of the enemy, and throwing out well to the front and flank small parties to mask your movement, and to cut off all communication with the enemy, by the people in their interest living on this side of the river. To divert suspicion it may not be amiss to have word given out that you are in pursuit of Jones's guerillas, as they are operating extensively in the Shenandoah Valley, in the direction of Winchester. He further suggests that you select for your place of crossing the Rappahannock, some point to the west of the Alexandria and Orange Railroad, which can only be determined by the circumstances as they are found on the arrival of your advance. In the vicinity of Culpeper, you will be likely to run against Fitz Hugh Lee's brigade of cavalry, consisting of about two thousand men, which it is expected you will be able to disperse and destroy without delay to your advance, or detriment to any considerable number of your command. At Gordonsville, the enemy have a small provost-guard of infantry, which it is expected you will destroy, if it can be done without delaying your forward movement. From there it is expected that you will push forward to the Aquia and Richmond Railroad, somewhere in the vicinity of Saxton's Junction, destroying along your whole route the railroad-bridges, trains of cars, depots of provisions, lines of telegraphic communication, etc. The general directs that you go prepared with all the means necessary to accomplish this work effectually. As the line of the railroad from Aquia to Richmond presents the shortest one for the enemy to retire on, it is most probable that he will avail himself of it, and the usually travelled highways on each side of it, for this purpose; in which event you will select the strongest positions, such as the banks of streams, commanding heights, etc., in order to check or prevent it; and, if unsuccessful, you will fall upon his flanks, attack his artillery and trains, and harass him until he is exhausted and out of supplies. Moments of delay will be hours and days to the army in pursuit.