The run-up to the Confederate attack is described by Emilio ( [BBR], pp.55-56):

Between the 10th and 16th there had arrived for the enemy from Georgia and North Carolina two four-gun batteries and six regiments of infantry. Beauregard also reduced his force on Morris Island and concentrated on James, under command of Brig.-Gen. Johnson Hagood. Gillmore still kept Terry there, inviting attack, although the purpose of the diversion had been accomplished. On the 15th the enemy demonstrated in front of the Tenth Connecticut pickets. It was rumored that two scouts had been seen about our lines. Some thought had been given to securing a line of retreat; for the engineers were reconstructing the broken bridge leading from James Island, and repairing causeways, dikes, and foot-bridges across the marshes along the old road to Cole’s Island, formerly used by the Confederates.

Companies B, H, and K, of the Fifty-fourth, under command of Captain Willard, were detailed for picket on the 15th, and about 6 P. M. relieved men of Davis’s brigade. Captain Russel and Lieutenant Howard, with Company H, held the right from near a creek, over rolling ground and rather open country covered with high grass and thistles. Captain Simpkins and Lieut. R. H. L. Jewett held the left of the Fifty-fourth line with Company K and a portion of Company B. It was over lower ground, running obliquely through a growth of small timber and brush. There was a broken bridge in the front. A reserve, consisting of the remainder of Company B, under Lieut. Thomas L. Appleton, was held at a stone house. Captain Willard’s force was five officers and about two hundred men. From Simpkins’s left to the Stono the picket line was continued by men of the Tenth Connecticut, holding a dangerous position, as it had a swamp in rear. Frequent showers of rain fell that evening. All night following, the enemy was uneasy. Lurking men were seen, and occasional shots rang out. Captain Willard, mounting the roof of the house, could see great activity among the signal corps of the enemy. He sent word to his officers to be vigilant, and prepared for attack in the morning.

About midnight the men were placed in skirmishing order, and so remained. Sergeant Stephens of Company B relates that George Brown of his company, a ” dare-devil fellow,” crawled out on his hands and knees and fired at the enemy’s pickets.

An attack was indeed impending, arranged on the following plan: Brig.-Gen. A. H. Colquitt, with the Twenty-fifth South Carolina, Sixth and Nineteenth Georgia, andĀ four companies Thirty-second Georgia, about fourteen hundred men, supported by the Marion Artillery, was to cross the marsh at the causeway nearest Secessionville, “drive the enemy as far as the lower causeway [nearest Stono] rapidly recross the marsh at that point by a flank movement, and cut off and capture the force encamped at Grimball’s.” Col. C. H. Way, Fifty-fourth Georgia, with eight hundred men, was to follow and co-operate. A reserve of one company of cavalry, one of infantry, and a section of artillery, was at Rivers’s house. Two Napoleon guns each, of the Chatham Artillery, and Blake’s Battery, and four twelve-pounders of the Siege Train, supported by four hundred infantry, were to attack the gunboats “Pawnee ” and “Marblehead ” in the Stono River.