HEADQUARTERS FIRST CORPS, Brady's House, near Herndon Station, June 18, 1863-4 p. m.

Major-General BUTTERFIELD,
Chief of Staff, Army of the Potomac:

My two signal officers were within 1 mile of Leesburg this morning at 10. 45. They report no force of any kind there, but Mosby's guerrillas from there up to Point of Rocks. They learn there from a man by name of Harper, that a man direct from Winchester yesterday reported that Longstreet had invested Harper's Ferry and demanded its surrender. General Slocum is moving up the pike, but will have trouble in crossing Goose Creek on account of the fords. Says in a note to me that he will go there to-night, and, if possible, to Leesburg to-night. My staff officer, Major [William] Riddle, who left here for your headquarters yesterday at 3 o'clock, has not yet returned. I thought you might have detained him for orders. I have heard from Meade of Pleasonton's fight. Howard had a staff officer here this morning. I sent two orderlies to you this morning, informing you of the position of the troops. Doubleday is along Broad Run, between the Church road and railroad, his headquarters at Nutt's.

Very respectfully, your obedient servant,

JOHN F. REYNOLDS,

Major-General of Volunteers, Commanding.

HEADQUARTERS ARMY OF THE POTOMAC, Fairfax Station, Via.,
June 18, 1863.

Commanding Officer Fifth Corps:

Nothing more new than you have from Pleasonton. They are getting sufficiently over their stampede to speak collectedly and coolly in Pennsylvania. About 1, 500 men (Jones, White, Imboden, & Co.) have had a round in that section. White was at Point of Rocks with 400 men last night, destroying cars. Six hundred of our cavalry from Dumfries, via Alexandria, should have reached the mouth of the Monocacy with a brigade and two regiments of infantry last night. Slocum by this time (3 p. m.) is in Leesburg. We don't exactly settle where Lee is yet. Headquarters to-night, Fairfax Court-House. Sedgwick is at Germantown. I send you to-day's Chronicle. Hancock is all up in good order at Sangster's Station. Catch and kill any guerrillas, then try them, will be a good method of treating them.

Very respectfully, &c.,

DANL. BUTTERFIELD,

Major-General, Chief of Staff.

HEADQUARTERS ARMY OF THE POTOMAC, Fairfax Station, Va.,
June 18, 1863-8 p. m.

Commanding Officer Cavalry Corps:

Your dispatch of 5. 30 a. m., covering second account of your fight, received; also communication touching Captain McKee and his detachment at the mouth of the Monocacy.