"Colonel PIATT, "

Chief of Staff.

A small detachment of First New York encountered a body of rebel cavalry at White Post, supposed to be the advance of force met by Twelfth Pennsylvania on Front Royal road. Two or First New York wounded, and 1 missing. One rebel killed and some wounded. A large rebel wagon train, with strong cavalry force, was discovered on Cedar Creek or Back road this morning . Have sent out heavy scouting parties on Cedar Creek, Front Royal, and Strasburg roads, well supported. Have not yet heard from Berryville. Am perfectly certain of my ability to holds this place .

"`R. H. Milroy, "`

Major-General . `"

"`Colonel PIATT, "`

Chief of Staff:

"` Enemy have appeared in considerable force on Cedar Creek, Strasburg, and Front Royal roads, and skirmishing going on. Nothing but cavalry appears yet . "Let them come . "

"`R. H. Milroy, "`

Major-General . `"

The court then adjourned to meet at 12 m. September 5, 1863 . TWENTY-SIXTH DAY. SEPTEMBER 5, 1863 . The court met pursuant to adjournment . Present, all the members and the judge-advocate . The testimony given yesterday by Major-General Schenck was read over to him, corrected, and his examination resumed, as follows:On the 13th of June, I received from General Halleck a dispatch dated 11 a. m., in reply to me inquiry of the day before, whether he had reliable information of rebel infantry being in the Valley . That dispatch is as follows:

"WAR DEPARTMENT, June 13, 1863-11 a. m.

" Major-General SCHENCK:

"Our cavalry scouts will probably be in to-day with more reliable information from the Valley. "

H. W. HALLECK,

" General-in-Chief

" I received also, later in that day, the following telegrams, viz:

" WINCHESTER, June 13, 1863 .

" Major -General SCHENCK:

" Considerable skirmishing with artillery all forenoon. McReynolds was attacked at Berryville this morning ; repulsed the enemy, but is falling back on this place, via Smithfield . It is reported that Stuart is crossing the run at Berry's or Snicker's Ferry. I fear the attack is only a feint to cover the great raid .

" R. H. Milroy,

" Major-General . "

"HARPER'S FERRY, June 13, 1863.

" Lieutenant-Colonel CHESEBROUGH:

"A messenger just from Charlestown reports that the enemy attacked Colonel McReynolds at Berryville this morning, and was repulsed, but that McReynolds subsequently fell back, by way of Smithfield, toward Winchester, and that shortly after he left, the rebel cavalry dashed in and burned the stores . If this reliable, it would seem as if it was not a movement in force, as they in that case would need all the stores they could get. Have you any information from Heintzelman or Stahel of the approach of the rebels?

" B. F. KELLEY, " Brigadier-General . "