As Major-General Quincy Gillmore departed the Department of the South in late April 1864, he left behind an assessment of the garrisons along the coast addressed to Brigadier-General John Hatch, his replacement. In that assessment, Gillmore included a paragraph describing the needs to defend the vital anchorage at Port Royal Sound:
The district around Port Royal Harbor, including Port Royal Island and Fort Pulaski, our depots on Hilton Head Island, and machine-shops at Land’s End, Saint Helena Island. Five thousand men would be ample for the defense of this district. Between 6,000 and 7,000 men will be available for it without risking other points. The town of Beaufort and our depot at Hilton Head are both well fortified. A permanent garrison of 200 experienced artillerists is enough for Fort Pulaski. The orders are to keep both draw bridges raised during the night time. Big Tybee Island is occupied by a picket sent from Fort Pulaski. Ample naval cooperation has been afforded in this district. Hilton Head and Port Royal Islands are surrounded by deep water, navigable by gunboats. An armed transport has always been attached to the command on Port Royal Island, and another to the command on Hilton Head Island for patrolling the waters.
Slightly exceeding Gillmore’s estimate of strength, April returns indicated 3,171 men present at Port Royal Island and 5,015 present in the Hilton Head district. Though that number would be reduced by the summer months. The Port Royal Island command, a brigade under Brigadier-General Rufus Saxton, included the 29th Connecticut (colored) Infantry, the 56th New York Infantry, 26th U.S.C.T., the 33rd U.S.C.T. (formerly the 1st South Carolina Volunteers), and Battery F, 3rd New York Light Artillery.
Separate from Saxton’s command was the Hilton Head District, consisting of garrisons on Hilton Head, Saint Helena Island, Seabrook Island, Fort Pulaski, and Tybee Island, under Colonel William W.H. Davis. At Hilton Head itself, Davis retained two infantry regiments (the 52nd and 104th Pennsylvania) with a battery from the 3rd Rhode Island Heavy Artillery and a company of the 1st New York Engineers. The 25th Ohio garrisoned Seabrook Island, protecting a vital coal depot and signal station. The Saint Helena Island garrison consisted of two USCT companies and an Invalid Detachment. At the mouth of the Savannah River, four companies of the 3rd Rhode Island and a company from the 9th USCT defended Fort Pulaski and Tybee Island. This left a battalion of the 4th Massachusetts Cavalry for patrols and a brigade of USCT (three regiments) under Colonel Thomas Bayley as maneuver elements.
Upon arriving at Port Royal, Hatch apparently required more information about the dispositions. Davis responded on this day (April 30):
Hdqrs. U.S. Forces, Hilton Head,
Fort Pulaski, Saint Helena, and Tybee Island,
Hilton Head, S.C., April 30, 1864.
Brig. Gen. John P. Hatch,
Comdg. Dept. of the South, Hilton Head, S.C.:
General: In answer to your verbal request that I report to you an estimate of the number of men required in this district for its proper defense, I have the honor to submit the following:
Post of Fort Pulaski and Tybee: Fort Pulaski, 250; Tybee Island, 50; total, 300. The defensive work on Tybee is a martello tower, armed with a 30-pounder Parrott and inclosed in an earthen parapet. This is more a picket of observation than for any other purpose, as the island can only be approached across wide marshes.
Hilton Head Island: Four regiments, with an aggregate strength of not less than 3,000 men, one-half of which at least should be white troops. Of these one regiment, say 800 to 1,000 men, will be required for the picket-line from Drayton’s plantation to Braddock’s Point, two-thirds of whom should be whites. One regiment should be within the intrenchments and two close at hand outside ready for any purpose whatever. The most important point on the picket-line is Seabrook, which by reason of its being the coal depot invites attack. Any serious defense required must be made at the line of intrenchments, hence the necessity of the main force being stationed near them. I do not believe the enemy will attempt anything beyond raids, but there should be preparations for a more serious attack. The picket-boats will enable the island to be held with a less force than would be otherwise required.
Saint Helena Island: Four companies, with an aggregate of 300 men, will be sufficient for this island, and I think it will be safe to place black troops there, for there is not much probability of the enemy landing while we have a gun-boat in Saint Helena Sound. As this island covers Bay Point the force now there, 25 men, I think sufficient for that point. For the district: Post of Pulaski and Tybee, 300; Hilton Head Island, 3,000; Saint Helena and Bay Point, 325: total force, 3,625.
I deem the above the maximum force that will be required for the defense of the district under any contingency likely to arise.
I remain, general, very respectfully, your obedient servant,
W. W. H. Davis,
Colonel 104th Pennsylvania Vols., Comdg. Post.
Davis and Saxton held small commands in the scope of the larger war effort in the spring of 1864. However their forces defended the important naval anchorage of Port Royal Sound. Without that harbor, the South Atlantic Blockading Squadron could not maintain the blockade. Two or three brigades worth of infantry, depending on the measure, for that duty. Hard to say those troops would have been better employed elsewhere, given the importance of the blockade. But those were 8,000 or so were there to enable particular strategic objectives.
(Citations from OR, Series I, Volume 35, Part II, Serial 66, pages 74, 76-77.)