HEADQUARTERS ARMY OF THE POTOMAC, July 12, 1863-11 a. m.

Major-General SEDGWICK:

The major-general commanding directs me to say that he presumes you are in communication with General Kilpatrick, and receive all the information he obtains respecting the enemy, and are governed accordingly in the disposition of your troops.

A. A. HUMPHREYS,
Major-General, Chief of Staff.

FREDERICK, MD., July 12, 1863-10. 15 a. m.

Received 11 a. m.

H. W. HALLECK,

General-in-Chief:

General Tyndale's brigade, consisting of the One hundred and sixty-eighth New York Volunteers and the One hundred and sixty-ninth and One hundred and seventy-second Pennsylvania Volunteers, arrived here yesterday afternoon, and soon after left for Middletown and Boonsborough, excepting a part of the One hundred and sixty-ninth Pennsylvania Volunteers, which remained to attend to the brigade stores and property, but will leave this morning. The One hundred and twenty-seventh and One hundred and forty-third New York Volunteers, all three-years' men, arrived here this morning, and are now preparing to leave for the front.

The delay which has occurred in the transportation of the above is owing to the railroad between the Relay House and this place being overstocked with trains (a greater portion of the road having but a single track), and to a want of men at this place in sufficient numbers to unload the trains rapidly as they arrive. Two hundred additional men are wanted for that purpose. The quartermaster says that civilians and negroes cannot be had. Can they be detailed from one of the regiments yet to arrive-say of the nine-month's men, if any?

GEO. THOM,

Colonel, and Aide-de-Camp.

[HAGERSTOWN, MD.,] July 12, 1863-10. 30 a. m.

General MEADE:

Our infantry occupies the town. One brigade of cavalry on the right and another on the left of town. General Wright's column of the Sixth Corps moved up from Funkstown, and his advance is within one-half mile of town, on our left.

The enemy had two pieces of artillery near the town, which they withdrew after firing a few shots. They have a battery of 20-pounder Parrotts in position on the Williamsport road, about 1 1/2 miles from town, which fired a few shots. The battery is supported by infantry, and the road is lined with skirmishers.

The best news I can find from Union men is that the enemy has taken position, his right resting on the Potomac, near Williamsport, his left within 1 1/2 miles from here, Longstreet commanding the right, Hill the center, Ewell the left, Stuart's cavalry covering the flank.