4. Two companies of Knap's battalion, Pennsylvania Artillery, will garrison Fort Sumner. One company of this battalion will garrison Fort Mansfield and the other Fort Simmons.

5. Major Knap's battalion will proceed at once to relieve the One hundred and seventieth Ohio National Guard. The commanding officer will report to Colonel Marble, commanding Second Brigade, at Fort Reno, for orders. The commanding officer of the First Brigade will furnish the transportation for this battalion and see that it leaves as soon as possible this evening.

6. Colonel Hayward, commanding First Brigade, will order one company of his regiment from Fort Bunker Hill to Fort Stevens, and one from Fort Lincoln to Fort Slocum.

7. Battery G, Third U. S. Artillery, will proceed without delay to Fort Sumner and report to the commanding officer for duty. The commanding officer of this company will at once make requisitions for muskets and equipments for his company, and send them to these headquarters by an officer for approval. The quartermaster of the Third Brigade will furnish the necessary transportation.

By order of Colonel Haskin:

R. CHANDLER,

Assistant Adjutant-General.

BALTIMORE, MD., July 4, 1864-11.35 a. m.

(Received 12 m.)

Honorable EDWIN M. STANTON,

Secretary of War, and

General H. W. HALLECK,

Chief of Staff:

General Weber telegraphs me from Harper's Ferry, at 10.48 this morning, that "the enemy are in sight. Our re-enforcements have not arrived. Two thousand cavalry and a force of infantry are in sight. I have been skirmishing two hours. If they press me much longer I shall retire to the Heights." At 11.05 our agent at Harper's Ferry telegraphs: "Great excitement here. All citizens leaving. Harper's Ferry is being evacuated by the military." Our agent at Washington telegraphs at 10.45 that troops for harper's Ferry are not yet started; that he had been ready for them since 3 o'clock this morning, and that they are waiting for ammunition and guns from arsenal. If ammunition cannot be sent at once from Washington there is doubtless a supply at Monocacy, which can be furnished them as they pass. A want of firmness is to be feared at Harper's Ferry. General Sigel reported himself at Shepherdstown Martinsburg. He stated that he would cross the river and march to Harper's Ferry this morning. General Weber states the rebel cavalry is under command of General Ransom, and was reported last night to be marching on Williamsport. He adds: "I egret to say that great damage will be done to the railroad." Your furnisher communication to the commandant at Harper's Ferry may aid in its preservation.

J. W. GARRETT,

President Baltimore and Ohio Railroad.