Emilio describes the beginning of the descent on James Island ( [BBR] pp.51-52):

All suspense regarding the employment of the Fifty-fourth ended July 8, with the receipt, about noon, of orders to move at an hour’s notice, taking only blankets and rations. Three hours after, the regiment began to embark, headquarters with seven companies finding transportation on the steamer “Chasseur,” the remaining ones on the steamer “Cossack,” with ColonelMontgomery and staff.

… A start was made late in the afternoon in a thunder-storm, the “Cossack ” stopping at Hilton Head to take on Captain Emilio and a detail of ninety men there. The following night was made miserable by wet clothes, a scarcity of water, and the crowded condition of the small steamers. About 1 A. M. on the 9th, the transports arrived off Stono Inlet; the bar was crossed at noon; and anchors were cast off Folly Island. The inlet was full of transports, loaded with troops, gunboats, and supply vessels, betokening an important movement made openly. General Gillmore’s plans should be briefly stated. He desired to gain possession of Morris Island, then in the enemy’s hands, and fortified. He had at disposal ten thousand infantry, three hundred and fifty artillerists, and six hundred engineers; thirty-six pieces of field artillery, thirty Parrott guns, twenty-seven siege and three Cohorn mortars, besides ample tools and material. Admiral Dahlgren was to co-operate. On Folly Island, in our possession, batteries were constructed near Lighthouse Inlet, opposite Morris Island, concealed by the sand hillocks and undergrowth. Gillmore’s real attack was to be made from this point by a coup de main, the infantry crossing the inlet in boats covered by a bombardment from land and sea. Brig.-Gen. Alfred H. Terry, with four thousand men, was to make a demonstration on James Island. Col. T. W. Higginson, with part of his First South Carolina Colored and a section of artillery, was to ascend the South Edisto River, and cut the railroad at Jacksonboro. This latter force, however, was repulsed with the loss of two guns and the steamer “Governor Milton.”

Late in the afternoon of the 9th Terry’s division moved. The monitor “Nantucket,” gunboats “Pawnee” and “Commodore McDonough,” and mortar schooner “C. P. Williams” passed up the river, firing on James Island to the right and John’s Island to the left, followed by thirteen transports carrying troops. Col. W. W. H. Davis, with portions of his regiment — the One Hundred and Fourth Pennsylvania — and the Fifty-second Pennsylvania, landed on Battery Island, advancing to a bridge leading to James Island.