The movement of the gunboats commenced at 3 o'clock, and progressed according to the plan for about thirty minutes, when the fort opened on the Sachem and Arizona, and in a few minutes put a shot through the boilers of the Sachem, killing and wounding many of her officers and men. She soon afterward hoisted a white flag. The Arizona was during part of this time aground.

The Clifton steamed slowly up her channel, firing slowly, and finally lay with her broadside toward the fort, engaged at close quarters. A shot went through her steam-pike shortly afterward, disabling her, but she fought gallantry for ten minutes more, when she, too, surrendered.

As soon as she hoisted the white flag, the Arizona and Granite City steamed over the bar; the Arizona grounded, but got off during the night.

General Weitzel's report, herewith inclosed, shows wy that part of the engagement assigned to him could not be carried out.

After the engagement, my situation was as follows: I was in the mouth of the Sabine Pass with seven transports. These contained 1.200 infantry, which could be landed; twelve guns and fifty wagons, which could not be landed. The enemy had a heavy battery of six guns, two gunboats, and a field battery within 6 miles, and was being rapidly re-enforced. We had nothing to protect us, except the fire from the guns on our transports, which would have been of little use against the enemy's gunboats.

The enemy's battery commanded the whole landing, and he could, with his battery and gunboats, have destroyed us at any time.

The remainder of my force was outside the bar in vessels, all of which had to be lightened, and at least three days would have been required to land it.

The stock of fresh water was nearly exhausted, and the animals were already on shirt allowance of water; the men were living on uncooked rations, and there was no fuel on shore for cooking.

No fresh water could be obtained unless the fort was in our possession, and the day's experience had taught me that no attack which I could make with the troops which I had been able to get across the bar could possibly succeed. It would have been absurd to have attempted to have passed the fort with the troops already inside of the bar, there being but one means of access to Sabine City, and this commanded for 1 1/2 miles by six heavy guns and whatever field artillery the enemy might have. There was not time to send to New Orleans to get instructions, and I therefore concluded to recross the bar and return to the mouth of the Mississippi.

I arrived at the mouth of the Mississippi this morning, having left Sabine Pass on the 9th instant, and believe there have been no losses except those reported by General Weitzel, and 200,000 rations thrown overboard from the Crescent (the grounded transport), to get her off the bar, where she would have been taken by the enemy, and 200 mules thrown overboard from the Laurel Hill, a steamer which had lost her smoke-stacks on account of the heavy sea. The loss of the mules will be investigated, as they were thrown overboard without orders from any responsible officer.

Very respectfully, your obedient servant,

W. B. FRANKLIN,

Major-General, Commanding.

Major General N. P. BANKS,

Commanding Department of the Gulf, New Orleans, La.