Militia, assisted by three gunboats and a transport, under Lieutenant-Commander Gillis, U. S. Navy. The main purpose of the expedition is to destroy the foundry, where, it is said, shot and shell, guns, and other instruments of rebellion are manufactured. In addition to that, all collections of supplies for the rebel army will be captured or destroyed. Horses and mules fit for the saddle, or for draught, also sheep, cattle, and swine fit for slaughter, will be captured as far as practicable. It is strictly forbidden, however, to take anything, or to destroy anything, not useful to troops in the field. As this expedition is intended to penetrate far within the enemy's lines, the infantry are expected to set out with a determination to achieve success at any cost. Volunteers will be called for, to move at thirty minutes' notice, and the commanding officer will be designated at the moment of departure. The men will carry nothing but their overcoats, canteens, and cartridge-boxes, with at least 50 rounds per man.

E. D. KEYES,

Major-General.

P. S. - Lieutenant Colonel C. Carroll Tevis is the commander of the infantry, and will be obeyed accordingly. Agreeably to the above instructions, the expedition got under way about thirty minutes after I had given verbal notice to the regiments to send their quotas, and appears to have been a perfect surprise to the enemy. Lieutenant-Colonel Tevis, Fourth Delaware, a copy of whose report is inclosed, conducted the land force with great skill and spirit. He penetrated, with a few hundred infantry, far within the enemy's lines, and to within 23 miles of Richmond, and, while in the neighborhood of at least twenty times his own numbers of the Confederate army, destroyed a foundry for guns, shot, &c., besides large stores of machinery, grain, &c. He also captured a large herd of beeves, and many horses and mules, but, for want of time for embarkation, he was obliged to leave them. It is by such splendid daring as that displayed by Lieutenant-Colonel Tevis and his command, that the enemy is crippled and confused, while our own men are rendered warlike and confident. I am also happy to be able to speak in praise of the skill and effect with which Lieutenant-Commanders Gillis and [John G.] Mitchell, of the U. S. Navy, and Captain J. C. Lee, of the Ninety-ninth New York Volunteers, aided with their gunboats in the success of the expedition.

I have the honor to be, sir, your most obedient servant,

E. D. KEYES,

Major-General,

Commanding Fourth Army Corps.

Major General JOHN A. DIX, Commanding Department of Virginia.

P. S. - The expedition brought in about 100 contrabands.

Numbers 2. Report of Lieutenant Colonel C. Carrol Tevis, Fourth Delaware Infantry, commanding expedition.

CAMP GILPIN, Gloucester Point, Va., June 6, 1863.

COLONEL: I have the honor to report you that the expedition under my command, composed of details of 100 men each from the