UNITED STATES FLAG-SHIP BENTON,

Island Numbers 10, April 8, 1862.

Major-General HALLECK:

SIR: I have the honor to inform the department that since I sent the telegraph last night announcing the surrender of Island 10 to me possession has been taken of both the island and the works upon the Tennessee shore by the gunboats and the troops under command of General Buford. Seventeenth officers and 368 privates, besides 100 of their sick and 100 men employed on board transports, are in our hands unconditional prisoners of war.

I have caused a hasty examination to be made of the forts, batteries, and munition of war captured. There are eleven earthworks, with seventy heavy cannon, varying in caliber from 32s to 100 pounders rifled. The magazines are well supplied with powder, and there are large quantities of provisions. Four steamers afloat have fallen in our hands, and two others, with the rebels gunboat Grampus, are sunk, but will be easily raised. The floating battery of sixteen heavy guns turned adrift by the rebels is said to be lying on the Missouri shore below New Madrid.

The enemy upon the main-land appear to have fled with great precipitation after dark last night, leaving in many cases half-prepared meals in their quarters, and there seems to have been no concert of action between the rebels upon the island and those occupying the shore, but the latter fled, leaving the former to their fate.

These works, erected with the highest engineering skill, are of great strength, and with their natural advantages would have been impregnable if defend by men fighting in a better cause. A combined attack of the naval and land forces would have taken place this afternoon or to-morrow morning had not the rebels so hastily abandoned this stronghold. To mature these plans of attack have absolutely required the past twenty-three days' preparation. General Pope is momentarily expected to arrive with his army at this point, he having successfully crossed the river yesterday under a heavy fire, which no doubt led to the hasty abandonment of the works last night.

I am unofficially informed that the two gunboats which so gallantly run the fire of the rebel batteries a few nights since yesterday attacked and reduced a work of the enemy opposite New Madrid mounting eight heavy guns. I regret that the painful condition of my foot, still requiring me ti use crutches, prevented me from making a personal examination of the works. I was therefore compelled to delegate that duty to Lieutenant-Commanding S. L. Phelps, of the flag-ship Benton.

A. H. FOOTE,

Flag-Officers, Commanding Naval Forces Western Waters.

CAMP ON EAST SIDE MISSISSIPPI RIVER,

April 8, 1862 - 7 a. m.

Major-General HALLECK:

Island Numbers 10 was hastily evacuated last night and the forces are trying to get off. Whether they will succeed remains to be seen. Paine's division is in advance. I have not heard from him since last night; everything the enemy had is ours at all events. It may be