On September 5th, the signals between General Gillmore and Admiral Dahlgren apprised General Ripley of an intended boat attack by way of Vincent's creek on Battery Gregg, to be made that night. Gregg was accordingly ready for it. It came about 1:30 o'clock on the morning of the 6th, and is reported by Captain Lesesne as follows:
I ordered the guns trained on the most probable point of attack, double loaded with canister, one 10-inch gun bearing on the beach in front and one on the extreme point in rear. Two 12-pounder howitzers were placed on the beach to the right of the work (under Lieut. E. W. Macbeth, First regular infantry) from the right of Battery Gregg to the beach. The artillery was supported by Major Gardner, commanding the Twenty-seventh Georgia. The enemy advanced from the point in about twenty boats; when within 100 yards of the beach I opened upon them with the 10-inch gun, followed by the howitzers. The infantry commenced firing shortly afterward. The enemy returned the fire with their boat howitzers and musketry. A few succeeded in landing but quickly returned to their boats. After the fire had been kept up for about fifteen minutes the whole force retreated. Our casualties were 1 man mortally and 5 slightly wounded.
General Gillmore signaled to Admiral Dahlgren, who had furnished the boats and crews, that he found Gregg prepared for the attack and had failed.
During the siege of Wagner, General Gillmore had established a picket post at the mouth of Vincent's creek, on the James island side. Lieut.-Com. A. F. Warley, of the Chicora, with a launch and crew, and Capt. M. H. Sellers, with a detachment of the Twenty-fifth South Carolina in boats, the whole under the guidance of J. Fraser Mathewes, attacked and captured this picket on the 4th of August, Captain Sellers losing one of his gallant followers. The night following, Lieut. Philip Porcher, on the unarmed steamer Juno, with a crew armed with rifles, was out along Morris island reconnoitering the fleet. Encountering an armed launch of the frigate Wabash, Porcher ran her down, attacked her crew with his rifles and received her surrender, with most of the crew. The launch was turned over to Commodore Tucker for his use in the harbor.