HDQRS. SECOND BRIGADE, FIRST CAVALRY DIVISION,
July 17, 1864 - midnight.

Major-General HUMPHREYS,

Chief of Staff:

GENERAL: Your dispatch of to-night received ant contents respectfully note. No sign of any movement on the part of the enemy can be discovered at this point, unless his unusual quiet should portend such. I would, however, respectfully call your attention to the fact that although my lines now stretch in nearly three-quarters of a complete circle (vedettes) from the left of the infantry around by Aiden's, Gurley's and Gary's Church to the plank road, and thence around on my left rear to near Sturdivant's Mill, yet the main road from Prince George to Lee's Mill, &c., is now uncovered, except by my patrols, as I understand all other pickets have been withdrawn between those points. From that road and between Prince George and this point there are at least main roads leading south, viz, one at Mount Zion Church, said to Disputanta Station, and one on this side of Blackwater, said to lead to Disputanta Station, and one on this side of Blackwater and the railroad, which runs nearly parallel with the Norfolk railroad. It is impossible for me with my command to go as far to my right rear as would effectually cover these approaches, as nearly my whole force is now on the long line I am obliged to hold. I will endeavor by patrols to discover any approach from that direction, but would recommend that some measures be adopted to effectually keep the road open toward Prince George. Previous to receiving your dispatch I had ordered a patrol to the Norfolk railroad at 3 a. m.; also to Lee's Mill. At dark to-night no movement or sign could be seen at the latter place. At 6 p. m. the enemy advanced a small party up the plank road to my outposts, but did not attack.

Very respectfully, your obedient servant,

THOS. C. DEVIN,

Colonel, Commanding Brigade.

HDQRS. CAVALRY CORPS, ARMY OF THE POTOMAC, July 17, 1864.

Brigadier General J. H. WILSON,
Commanding Third Cavalry Division:

GENERAL: The major-general commanding directs that a regiment from your division be sent to Prince George Court-House to-day to relieve a regiment of the First Cavalry Division on picket at that point.

Very respectfully, your obedient servant,

F. C. NEWHALL,

Captain and Acting Assistant Inspector-General.

HEADQUARTERS THIRD DIVISION, CAVALRY CORPS, July 17, 1864.

Colonel J. B. McINTOSH,
Commanding First Brigade:

COLONEL: You will please detail a regiment from your command to relieve Lieutenant-Colonel Hutchins, with the First New Hampshire Cavalry, on picket at Cocke's Mill, to-morrow morning at 6 o'clock; the men to be provided with three days' rations and forage.

By command of Brigadier-General Wilson:

L. SIEBERT,

Assistant Adjutant-General.