I have been all over the works and found them as follows:—One fort on a point of rocks seventy-five feet high, calculated for six or seven guns, mounting two seven inch rifles, and one eight-inch and one Parrott gun on wheels, which was carried off. On the left of this work is a triangular work, calculated to mount one heavy gun. These works are connected with another fort by a covered way and double rifle pits extending one quarter of a mile, constructed with much labor, and showing great skill on the part of the constructor. The third fort commands the river in all directions. It mounted one splendid Blakely one hundred-pounder, one eight-inch and two thirty-pounders. The latter were lying bursted or broken on the ground. The gunboats had so covered up everything with earth that it was impossible to see at first what was there, with the exception of the guns that were dismounted or broken. Every gun that fell into our hands was in good condition, and we found a large quantity of ammunition. These are by far the most extensively built works, with the exception of those at Vicksburg, I have seen yet, and I am happy to say that we hold them. I am dismounting the guns, and getting on board the ammunition. Since making the above examination new forts have been passed nearly finished. They had no guns, but were complete as regards position, and had heavy field pieces in them. DAVID D. PORTER, Acting Rear Admiral, Commanding Mississippi Squadron. CAPTURE OF PORT GIBSON, MISS. MAY 1, 1863. Two days after the bombardment of Grand Gulf by Admiral Porter’s fleet, General Grant’s forces made a successful attack on Port Gibson, a point six miles in the rear of Grand Gulf, which compelled the rebels to evacuate the latter place. General Grant sent the following dispatch to General Halleck, dated May 3: GRAND GULF, Miss., May 3, 1863. Major-General HALLECK, General-in-Chief: We landed at Boulingsburg April 30, moved immediately on Port Gibson, met the enemy eleven thousand strong, four miles north of Port Gibson, at two o’clock A. M. on the 1st inst., and engaged him all day, entirely routing him, with the loss of many killed, and about five hundred prisoners, beside the wounded. Our loss is about one hundred killed, and five hundred wounded. The enemy retreated towards Vicksburg, destroying the bridges over the two forks of the Bayou Pierre. These were rebuilt, and the pursuit has continued until the present time. Besides the heavy artillery at this place, four field pieces were captured and some stores, and the enemy were driven to destroy many more. The country is the most broken and difficult to operate in I ever saw. Our victory has been most complete, and the enemy are thoroughly demoralized.