At five A. M. the Union fire opened upon the batteries on Morris Island, being directed from the entire line of works recently erected on Folly Island. The rebels were taken by surprise, and as the fire from the Union ranks poured in upon them, they sprang to the tops of the sand-hills, eagerly looking whence it came, but speedily dropped back again, and remained concealed till they were taken prisoners by the Union troops. The fleet, with Admiral Dahlgren on board the Catskill, had, at an early hour in the morning, crossed the southern channel, and had drawn up in line of battle along the southern end of Morris island, in order to deliver an enfilading fire and harass the enemy on his left and rear. A vigorous fire was also kept up, during the greater part of the day, upon Fort Wagner. For three hours the cannonading continued against the Morris island works, and when at length it began to slacken, General Gilmore signalled to General Strong, who with his little boat fleet lay concealed in Folly river, to land his forces, and assault and carry the batteries at the point of the bayonet. The order was no sooner given than executed. With shouts and cheers the troops sprang ashore, formed in line of battle, with the Sixth and Seventh Connecticut on the right, the Ninth Maine and Seventy-sixth Pennsylvania in the centre, and the Third New Hampshire and the Forty-eighth New York on the left. In less than ten minutes the right and centre had carried all the batteries, and left all the rifle-pits—capturing ten Columbiads, two 10-inch mortars, one Whitworth gun, together with nearly the entire garrison, consisting of the First South Carolina Artillery, and ten companies of the Twenty-first South Carolina Volunteers, in all numbering one hundred and eighty-five men. This unexpectedly quick and brilliant success in capturing these strong works, and obtaining so important a footing upon the island, filled the troops with the greatest enthusiasm. Cheer after cheer rent the air. In a few moments General Gillmore and staff crossed to the island, and, under a burning sun, examined the works, and ascertained the extent of the victory. The batteries had been in command of Captain Mitchell, son of the Irish orator, John Mitchell. With the exception of Fort Wagner and Cummings’ point, all the works on Morris island had been taken by this time; and during the whole afternoon the monitors continued to throw shell into the fort. It was determined that at daylight on the following morning, an attempt should be made to carry Fort Wagner at the point of the bayonet. THE ASSAULT ON FORT WAGNER. JULY 11, 1863.