part of the transports might return for the DIVISION of Hovey-6,000 strong. They did not get here until daylight this morning, when the troops being ready to land as soon as the batteries were silenced, the gunboats opened the attack at 8 a. m. precisely. Seven gunboats, all iron-clads, were engaged. The Price was kept out of the fight, being employed to tow the Anglo-Saxon (steamboat), whose wheel, damaged by running the Vicksburg batteries, it had been impossible to repair.

It was found that the enemy had five batteries, the first and most formidable of them being placed on the high promontory next to the embouchure of the Big Black. In this battery there were four guns, of which, after a constant fire of five hours from the gunboats, only one has been dismounted. The work is placed in a shoulder of the hill about 30 feet above the river. It is entirely open, protected only by a parapet, behind which the heads of the gunners can be seen as they load their pieces. These, as Captain [James A.] Greer, of the gunboat Benton, informs me, are 100-pounder rifles. The lower batteries, mounting smaller guns and having no more than two pieces each, were silenced early in the action, but this one obstinately resisted to the last, the gunboats finally withdrawing at about 1. 30 p. m. For the last four hours the whole seven to drop shells within the parapet, now at the very foot of the hill, within about 200 yards, seeking to dismount its guns by direct fire. It was hit again and again, but its pieces had not been disabled when Admiral Porter gave the signal to withdraw. There was some reason to believe that it was short of ammunition, but this could not be certainly known. The gunboats were hit more or less severely. I was on board the Benton, and saw that her armor had repeatedly been pierced both in her sides and her pilot house, but she had not a gun disabled, and, except the holes through her mail (some of them in her hull), was as ready to fight as at the beginning of the action. Of the other vessels, the Tuscumbia had her hog-chains cut, but the others are reported as substantially uninjured. The Mound City received but three hits. On the Benton, 7 men were killed and a few wounded. The other casualties are not yet reported. The Lafayette remains under the fort, and firing is still kept up occasionally.

The batteries having thus proved too much for the gunboats, General Grant determined to execute an alternative plan, which he had in mind from the first, and accordingly had the troops all to disembark from transports and march across the neck of land in front of Grand Gulf, distance 1 1/2 miles, to a point below, out of range of its guns. The transports are to be run past the batteries as soon as it is dark, under cover of renewed attack from the gunboats. The troops will then be embarked, and either landed at Grand Gulf, just below the batteries, or else carried down to Rodney and marched into the rear of Grand Gulf by way of Port Gibson. I judge the latter move will be adopted. General Grant, however, is in favor of a direct assault on Grand Gulf. The whole of the Thirteenth Army Corps is now here, A. J. Smith's DIVISION having arrived by land, marching around Saint Joseph's Lake. Of the SEVENTEENTH Corps, Logan's DIVISION has also arrived by the same road, while Quinby's close at hand, and McArthur's will be at the place of embarkation before morning.

There can be no difficulty in throwing 35,000 troops across the river into Rodney before morning of May 1. The enemy have about 10,000 troops in Grand Gulf. The weather continues fine. General Thomas in here assisting General Grant as much as possible.