It would be well to have them either paroled or otherwise disposed of, as Frederick is an inconvenient place for them. Information this moment received completely confirms the rout and demoralization of the rebel army. General Lee is reported wounded and Garland killed. Hooker alone has over 1,000 more prisoners. It is stated that Lee gives his loss as 15,000. We are following as rapidly as the men can move.

GEO. B. McCLELLAN,

Major-General, Commanding.

CAMP NEAR BOONSBOROUGH, MD.,

September 15, 1862.

Lieutenant General WINFIELD SCOTT, West Point:

We attacked a large force of the enemy yesterday, occupying a strong mountain pass, 4 miles west of Middletown. Our troops, old and new regiments, behaved most valiantly and gained a signal victory. R. E. Lee in command. The rebels routed, and retreating in disorder this morning. We are pursuing closely and taking many prisoners.

GEO. B. McCLELLAN,

Major-General.

WASHINGTON, D. C., September 15, 1862-3 p. m.

Honorable J. K. DUBOIS, Springfield, Ill.:

I now consider it safe to say that General McClellan has gained a great victory over the great rebel army in Maryland, between Fredericktown and Hagerstown. He is now pursuing the flying foe.

A. LINCOLN.

HEADQUARTERS ARMY OF THE POTOMAC,
September 15, 1862.

General BURNSIDE:

GENERAL: Reliable intelligence received by General Hooker, and by him communicated to these headquarters, represents a demoralized condition of the enemy, who are retreating in disorder toward the Shepherdstown Ferry. They confess to have been seriously defeated yesterday.

If, as you advance, you find this information to be corroborated, the general wishes you to follow the enemy up by Porterstown and Sharpsburg. Keep open your communication with Sumner, on the right, and Franklin, on the left. Take no wagons with you except ammunition wagons and ambulances. Use effectual precautions to make it certain that your baggage wagons will be kept out of the road. They will be sent forward as soon as practicable, by orders from here.

The foregoing is communicated by command of Major-General McClellan.

Very respectfully, your obedient servant,

[S. WILLIAMS,]

Assistant Adjutant-General.