JUNE 21, 1863-12. 10 a. m.

General TYLER, Sandy Hook:

General Hooker desires to know where your cavalry are, how many, and what they are doing. He has a corps at Leesburg, and can relieve you if attacked. Our signal officers at Leesburg can see signals from Sugar Loaf Mountain. The enemy read our signals unless in cipher. We have 750 cavalry at the Monocacy and fords.

DANL. BUTTERFIELD,

Major-General, Chief of Staff.

HDQRS. CAVALRY CORPS, June 21, 1863-3 a. m.

(Received 9. 30 a. m.)

Brigadier-General WILLIAMS,
Adjutant-General:

GENERAL: Your dispatch of 5. 20 p. m. yesterday wa received. I shall do my best to accomplish the general's views. With regard to A. P. Hill's troops, a prisoner of the Cobb Legion, captured at Warrenton yesterday, states that he was just from Culpeper, and that there were very few troops at that place, the whole rebel army having marched up the Rappahannock, and gone to the mountains. Longstreet's corps, I am satisfied from what prisoners and others say, is now in the Shenandoah Valley. The prisoner above mentioned stated that two regiments of the Legion had been left-one at Stafford Court-House, the other at Fredericksburg. To-day's operations ought to give us more information. The main body of the rebel infantry is in the Shenandoah Valley. I have this from the people of the country. A. P. Hill is not north of the Rappahannock, and is either guarding that river or is on his way up the Valley. His corps was the last to move. No persons are permitted by the rebels to come from the Blue Ridge this way, and the gaps are all guarded. My opinion is, that Stuart's force is kept in our front as a blind until their main force is thrown across the Potomac; they will then turn westward toward Pittsburgh. Had they obtained possession of Aldie, from what they say I think they would have attacked the army here by this time; but [our] holding this gap exposes all their force as it marches through Loudoun, and it strikes me they have given that up, for the present, at least. Very respectfully,

A. PLEASONTON,

Brigadier-General, Commanding.

[P. S.]-The people here are bitter, and I am very close with them.

HEADQUARTERS ARMY OF THE POTOMAC, June 21, 1863-8. 35 a. m.

Major-General STAHEL:

The major-general commanding directs that you make, without dally, a reconnaissance in force in the direction of Warrenton and the Upper Rappahannock. He desires that you will go to Warren-