BALTIMORE, MD.,

September 7, 1862-7.30 a. m.

Major General H. W. HALLECK:

Colonel Dennis, at Gettysburg, communicates the following information, from undoubted authority:

Brigadier General B. [T.] Johnson, with 5,000 infantry, came into Frederick about 12 m. yesterday. General Jackson followed with 25,000 at 2.30 p. m. Three batteries of artillery only were seen. Johnson's brigade encamped a mile north of the city; his troops much jaded. He said he would be there only one day; then for Pennsylvania or Baltimore. General Bragg was advancing up the Shenandoah Valley for Pennsylvania, with 40,000 troops.

Colonel Dennis' informant said, when he asked where the cavalry was, the reply was that they would be heard from in Pennsylvania. Johnson came into Frederick over Georgetown Bridge, 3 miles south of Frederick.

JOHN E. WOOL,

Major-General.

MARTINSBURG, VA.,

September 7, 1862-8 a. m.

Major-General WOOL:

Five hundred rebel cavalry attacked my outposts this morning. It may be the advance of a larger force.

JULIUS WHITE,

Brigadier-General.

MARTINSBURG, VA.,

September 7, 1862-10 a. m.

Major-General WOOL:

My outposts are attacked. I do not yet know whether the attack is formidable or not. Will advise you as soon as I know. You may rely on your orders being executed, and if you have frequent reports from me, you must not think we are excited, though our troops are all raw. I shall obey the order to fight, though with no hope of support.

JULIUS WHITE,

Brigadier-General.

MARTINSBURG, VA.,

September 7, 1862-11 a. m.

Major General JOHN E. WOOL:

No reliable news. The enemy (one division) is in front of Berlin. My impression is that it is a foraging party covering left flank of their army, which has crossed, and is still crossing, into Maryland, below Point of Rocks. Three brigades are marching on you, so I was informed several days ago. It may turn out true. A long range of camp-fires was seen in your direction this morning. I will send up to the observatory to look out for dust, and I will inform you.

D. S. MILES.

I send you the above copy of a dispatch from Colonel Miles, Harper's Ferry. His position will not be attacked. I respectfully suggest that he support this post with a re-enforcement of four regiments of infantry and two batteries. I have but three 6-pounder guns.

JULIUS WHITE,

Brigadier-General.

(Same to Halleck.)