The failure to establish a line on “the ridge” did not set well among the Federals directing the siege lines on Morris Island on August 25, 1863. On the barrier island a sand dune which might be inconsequential on any other battlefields now took on the prominence of a major mountain. Without the ridge, the siege lines were stalled. Again, turning to the map provided by Colonel Edward Serrell, the ridge was at a particular point where the marsh cut into the island and constricted any forward movement.
After being pushed back from the ridge on August 21, Major Thomas Brooks directed his subordinates to construct a redan on the left end of the fourth parallel, where the ruins of the McMillian house stood on a rise of sand. The Federals began conversion of the cistern found in the ruins into a bombproof. The redan on the left included a Billinghurst-Requa gun. That was one of three moved up to the fourth parallel. Lieutenant J.S. Baldwin built a parapet of gabions over a dike leading to St. Vincent’s Creek, to provide some security for the exposed Federal left. The profile of that work follows the line r-r’ on the map.
Early attempts to advance the sap roller met grapeshot and canister from Battery Wagner. That line terminated not far from where it started near the redan.
On August 25, the Federals attempted to blast the Confederates off the ridge. The engineers built positions for three Coehorn mortars and a bombproof and a boat howitzer, labeled a 30-pdr but likely a 24-pdr. Ensign James Wallace of the Navy commanded the boat howitzer, giving this operation “joint” credit, for those of you operating under the Goldwater-Nichols Act. The positions of the mortars and the howitzer actually enfiladed the ridge. Supporting this small bombardment, compared to others on Morris Island, were four 8-inch mortars from the third parallel.
The bombardment started at 5:30 p.m. but did not deliver any significant gains. Confederate counter-battery fire from Battery Wagner and all the way from James Island proved formidable. A planned infantry assault to follow the barrage failed to move. Confederate reinforcements to the ridge strengthened their hold after dusk.
After these failures, on August 26 Brigadier-General Quincy Gillmore turned to the infantry. Over some of the same ground which the July 11 and July 18 assaults had crossed in their race for Battery Wagner, he ordered General Alfred Terry, commanding the division on Morris Island, to send in another attack. This time the objective was closer, with limited expectations. Preceding the infantry assault, a concentrated bombardment kept the guns in Wagner silent and the heads of Confederate sharpshooters down. Brooks recorded the results:
The general commanding ordered General Terry to take and hold the ridge, and placed the resources of the command at his disposal for that purpose. It was accomplished at 6.30 p.m., by a brilliant charge of the Twenty-fourth Massachusetts Volunteers, Col. Francis A. Osborn commanding, supported by the Third New Hampshire Volunteers, Captain Randlett commanding. Sixty-seven prisoners were captured. They were afraid to retire on account of their own torpedoes, as they informed us, and had too little time, even if there had been no torpedoes. No works, excepting rude rifle-pits in the excellent natural cover afforded by the ridge, were found. Sand-bags of a superior quality had been freely used for loop-holes and traverses.
From the Confederate perspective Colonel George Harrison, commanding Battery Wagner, related:
About the middle of this afternoon, the enemy’s fire on this place and Battery Gregg became quite warm, and about an hour before sunset they concentrated their whole fire on this work and our rifle-pits in front. This fire was not only exceedingly rapid, but very accurate, the enemy using every variety of projectiles. This fire continued about half an hour, when I discovered that my pickets had opened from the rifle-pits. This was immediately followed by volley after volley of musketry for about five minutes, when it partially ceased. As soon as it commenced, however, I ordered the night pickets, consisting of 175 men, to form immediately to march to the support of the pits (this picket generally relieves and supports the pits at dark, it was then not yet sundown). I soon discovered that the partial cessation of musketry above alluded to was owing to the fact that the enemy had overwhelmed and captured a portion of our pits to the right, being distant from theirs only about 30 yards. Our pits on the left held out but a few moments longer; in fact, in ten minutes from the fire of the first musketry the enemy were in possession of our pits. From two officers and a number of men who escaped from the rifle-pits, I ascertained that the enemy’s attacking party were at least 1,500 men, while our picket consisted of 86 men from the Sixty-first North Carolina Troops, under command of First Lieut. William Ramsey, who was among those who made their escape.
The volleys reported by Colonel Harrison were actually the Billinghurst-Requa guns opening up to cover the assault. The action was certainly not a textbook affair. Hardee’s Tactics, nor Scott’s for what it is worth, provided a “school” for such maneuvers.
The Federals immediately started building a trench line across the ridge to form the fifth parallel. The line ran 140 yards from the beach to the marsh. “In this work, the Twenty-fourth Massachusetts Volunteers proved themselves as efficient in the use of the shovel as they had in that of the bayonet a few moments before,” wrote Brooks. Even captured Confederates were ordered to help dig out the line. Improvements started that night included Requa positions on both ends of the line. The following day came approval to construct siege mortar positions in the fifth parallel so as to avoid needless firing over the heads of the advanced parties. A bombproof for those mortars was recorded with profile s-s’ on Brooks’ map.
The engineers also built approaches connecting the fourth and fifth parallels using the flying sap method that night. Much of this work, under the direction of Lieutenant Charles Wilcken, was done by the 3rd USCT. One boyaux from started from the redan on the left of the fourth parallel. The profile of that trench was recorded along the line of t-t’ on Brooks’ map:
Note the banquette step in the trench. Like others in the advanced works, this was a “keep.”
The other boyaux extending from the right of the fourth parallel contended with water from the tides. It’s profile was the line of o-o’ on the map.
This trench used a ditch on the right side of the advance. Its angle, as it approached the ridge, avoided any enfilading from both Battery Wagner or James Island.
The evening assault and night work established the last parallel the Federals would need on the approach to Battery Wagner. Mortars now lay within easy reach of the Confederate works. The Federal siege lines were accomplishing what two open assaults had not – push the Confederates off Morris Island.
(Citations from OR, Series I, Volume 28, Part I, Serial 46, pages 296-7 and 499-500.)