The Official Dispatches

Washington. Feb. 9. —A bearer of official dispatches from the fleet off Charleston has arrived here. The following is from rear admiral Dupont concerning the rebel attack on our squadron off that port:—

Admiral Dupont’s report.

Flag Ship Wabash, Port Royal, Feb. 2.

Sir : I have to report that about 4 o’clock on the morning of Jan. 31st, during the obscurity of a thick haze, two iron-clad gunboats came out of Charleston by the main ship channel unperceived by the squadron, and commenced a raid upon the blockading fleet. Most of the latter were of the light class of purchased vessels; two of the heaviest men-of-war, the Powhattan and the Canandaigua, being at this port coaling and repairing.

The Mercedita was the first vessel attacked. Her officers and crew had been particularly watchful during the night to look out for suspected vessels, and at 3 o’clock had shipped her cable and overhauled a troop steamer running for the channel by mistake. She had returned to her anchorage, and Capt Stellwagen had gone to his room for a short time, leaving Lieut. Commander Abbott on deck, when one of the iron-clads suddenly appeared. Her approach was concealed by the haze and mist of the atmosphere. The vessel was immediately hailed, and an order given to fire, but the iron-clad being close aboard and lying low in the water, no guns could be brought to bear upon her.