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The construction of this battery required new techniques to overcome the problems created by doing construction on the surface of a marsh. New ways of driving down the pilings without the use of a steam-driven pile driver had to be considered. The use of a steam-driven or mechanical pile driver was out of the question for several reasons.

Provision would have had to be made for hiding it during the day and working it at night, or else it would be destroyed by continuous enemy fire.

After trying several pile driving techniques, two systems seemed more efficient than others, and these were used to drive down the pilings.

The first technique used, was to put a small square plank platform on the marsh surface, then load it down with sandbags. This platform was used as a counterweight. The sheet piling was then stood-up vertically, allowing it to sink part way down of its own weight. When it would sink no farther, a long cross pole, used as a lever, was positioned off-center on the piling, and tied twice around it.

The short end of the cross pole was then connected to the counterweight platform. Then a rope, which had been connected to the long end of the cross pole, was pulled on by about fifteen men. The cross pole become a large lever forcing the piling most of the way down into the mud, using the men's combined weight applied on the long end of the lever. Then the cross pole was repositioned, being tied to the piling on its center, and equal amounts of men on each end would drive the plank down into the substratum with heavy wooden mallets (Fig. 8)

This technique worked, but it took too much time to reposition the sandbag counterweight for each piling. Eventually a technique that was easier to accomplish, but equally effective was used.

Instead of the platform counterweight, this second technique involved standing the piling vertically as before, but the cross pole was tied at its center to the piling. With the cross pole centered on the vertical piling, leaving equal amounts on each end, the cross pole and piling formed a cross. Fifteen men on each end then pulled down on the cross pole with ropes.

When the piling was down as for as it would go, the cross pole was repositioned, and the piling driven the rest of the way with wooden mauls as described above. This technique was used to drive most of the pilings used in the construction of the gun platform. After all the pilings were driven into the mud, the tops were then cut evenly off. (Fig. 9)

The mud within the small square area, which was left open for the construction of the gun platform, was covered over with two layers of canvas tarp. Over the canvas tarps, 15 inches of "well-rammed" sand was packed. Directly on the sand were placed two layers of 3-inch pine plank laid diagonally to the intended line-of-fire. The lower two courses of plank rested on one another with the bottom course resting directly on the sand. The ends of the lower plank course also rested on a welting strip that was nailed to the interior of the sheet piling box.

Finally, over these two courses of 3-inch plank was laid a third course of 3-inch plank that covered the heads of the sheet piling, and rested on the two courses below it. The two lower courses were diagonal to, and the top course placed in the line of, fire. (Fig. 5)

As the weight of the sandbags used to construct the parapet increased on the outer platform of grillage work, forcing it down, the displaced mud under it compressed, forcing it laterally.

By this action, the pressure of the mud through and under the sheet pilings would have a tendency to force the gun platform upward, if it were to move at all, because the larger platform would have a much greater load per square foot than the smaller gun platform, which rested in the center square.

Thus if the parapet platform or "grillage" should begin to settle, or sink, sandbags could continually be piled upon it to keep the parapets at a safe height around the gun, while the up heaved mud would also form a natural glacis around it. The gun platform would essentially remain stable and in one relatively constant position independent of the grillage platform. Colonel Serrell was confident of his unique platform design and oversaw most of the work himself. (Fig- 7)

To provide the necessary access for the construction of the "Marsh Battery" as it was officially named, a causeway had to be constructed over the mud. The banks of the creeks were composed of oyster and other shellfish deposits and found to be firm enough to provide a stable docking and unloading point near the site.

The causeway ran from the creek bank in front, along the left edge of the battery, and curved around behind it. This left flank approach would also allow the road to be protected against enemy soldiers who might try to attack the battery during construction. (Fig. 6)


The causeway was used for delivery at all the construction materials and work parties, which were delivered by boats. The causeway was also constructed of trampled grass with logs and sandbags laid over it. As it settled into the mud more logs and pine planking was put down to provide smooth surface for rolling heavy objects and barrels.

As soon as practicable a plank walkway, suspended on a network of trellis, was built to the Marsh Battery from the angle of an existing road on Morris Island. near Black Island) After the night of August12 most of the men were marched over it, and this become the main access for the work parties (Fig. 10)

An additional platform was built on which 200 soldiers of the reserve infantry, or the "covering party," were positioned to provide additional security for the battery site.

As protection for the soldiers working on the Marsh Battery a dummy battery and work site was commenced in order to draw the enemies fire while the construction of the real battery remained secret. This dummy battery was set up several hundred yards in front of the main battery. The plan worked, and the decoy was continually bombarded while the construction on the main battery went relatively unhindered.

A magazine was constructed on the hard ground at the easterly end of the walkway on Morris Island, which was intended for supplying the Marsh Battery. Soldiers were fitted with yokes on their necks for carrying the gunpowder cartridges to the battery, but this technique was impractical and boats were used instead of men wearing yokes.

Since there were so many winding creeks, small boats patrolled the marshes to prevent a surprise attack that could come from almost any direction. These "picket boats" patrolled the creeks leading to James Island and Charleston harbor. Two naval boats with bow howitzers were also stationed in the same waters.

Each of these "Picket Infantry Boats" had several infantry men on board. The soldiers doing the construction felt a lot more secure once the "Picket Boats" began to patrol, and a surprise attack never occurred at the battery site.


During the night, a "boom" of heavy round pine logs, chained together, was put across the main supply creek, and securely anchored to the banks. It was designed to obstruct the passage of enemy boats that might attempt to come up the creek from Charleston harbor. (MAP 4)


At dawn on the 17th, the bombardment of Fort Sumpter began, and continued unabated for seven days. The bombardment of the former Federal fort was one of the most intense bombardments ever undertaken up to that time. During the first 24 hours the Union batteries fired 948 shell at the tort, with 678 of them being direct hits. By August 24, Gilmore would report Fort Sumpter was reduced to "a shapeless and harmless mass of ruins."

The completion of the battery was in itself an engineering feat. The British journal "ENGINEERING" claimed that the Marsh Battery was one of the "most important engineering works done by either army during the war. " Colonel Serrell must be credited with the design and construction of the battery and was assisted by Captain Charles P. McKenna, Lieutenant Nathan M. Edwards and Lieutenant Charles B. Parsons of the Volunteer Engineers. (Fig.6 & 7)

The construction of the battery required the following materials and labor:

13,000 sand bags (812 tons)

123 pieces, 15 to 18 inch diameter, yellow pine timber, 45 to 55 feet long. (307 tons)

5,000 feet 1 inch pine boards.

9,516 feet 3-inch plank. (Total: 28 tons of lumber)

8 tarpaulins, 18x28 feet each.

300 pounds 7 inch, and 300 pounds 4 inch, spikes and nails.

600 pounds round and square iron.

75 fathoms 3-inch rope. (450 feet)

The labor involved for the construction of the battery was as follows:

91 days work of Engineer Officers

1,384 days work of engineer soldiers

7,390 days work of infantry

172 days work of four horse teams

93 days work of boats

Average pressure on battery foundation: 513 lbs. per square foot

Average pressure on gun deck: 123 lbs. per square foot.

These quantities do not include the material or labor used for the construction of bridges, plank walks across the marsh, protective boom, or the road and pier at the engineering camp on Morris Island, which were necessary for the construction of the battery.


On the night of August 17, the Marsh Battery was ready to receive its gun, and Lieutenant Wadlie, of the Third New Hampshire Volunteers, and Lieutenant Parsons, of the Volunteer Engineers, made their preparations to put the gun in place. This was done by first carrying the timber parts, and then the iron work of the gun carriage, to the battery in boats, when the tide was high.

Finally, during the night, an 8-inch 200-pounder Parrott rifle was successfully transported over the marsh, and mounted in the battery. The transportation of the gun to its intended site was left to Lieutenant Wadlie. The following is his own statement regarding the events leading to the gun being mounted in the battery:

Wadlie:"I consented to undertake the loading, transporting, unloading, and mounting of the gun. That night I traced in a small boat the windings of the creek. The dangers were enough to unsteady ones nerves. The boat would be like an eggshell under the gun, and might easily land it at the bottom of the creek and irrecoverably loose it, and I might be Court-Marshaled. The boat was towed near its destination and then we waited two days and nights for the completion of the battery and the requisite landing place.

The gunwale was not more than about 5 or 6 inches above the water and we had to pump often. Finally the gun was rolled into the battery, the work of a night, and the next night it was mounted. I then reported to headquarters, where I was offered the command of it but declined on account of failing health. I was called upon later to lower the gun, and removed the wheels to obtain greater elevation."


The gun itself was a 8 inch, 200-pounder "Parrott rifle," designed by Robert P. Parrott, an ordnance engineer who designed the large-caliber rifled guns used by the Federal services. The gun was made of cast-iron and reinforced at the seat of the charge by a wrought-iron jacket or banding, which was shrunken on after the gun was cast. The jacket was heated to expand its diameter so it would fit over the breach area, then cooled. As it cooled the jacket would contract and grip the barrel almost as if the jacket had been welded on. This banding gave the gun the distinctive appearance characteristic of the Parrott design.

The gun was rifled with 11 groves, and weighed 16,577 pounds, or 8.28 tons. Regulation weight for such guns was 16,500 pounds, but the exact weight accompanied each gun, being stamped into the muzzle.

Captain Alfred Mordecai inspected the gun and verified its exact weight at the West Point foundry in Cold Springs New York, when it was cost in 1863. The length of its bore was 136 inches. (11'-4")

On the muzzle of the gun is stamped:

W.P.F., NO.6, 1863, WT.16,577, A.M.-The "A.M." means Alfred Mordecai, the guns inspector when it was cast.

The projectiles or shells fired from the gun ranged from 150-200 pounds depending if the projectile was a short, long shell, or a solid shot. The propellant cartridges used were woolen powder bags containing 20 lbs. of gunpowder.

The normal charge of powder for this type gun was 16 pounds, but to reach distant Charleston, 20 pound charges were used.

The gun cordage assembly weighed about 10,000 pounds, and the combined weight of gun and carriage assembly approximated 26,577 pounds or about 13.2 tons.

While the battery was nearing the end of construction, range and sighting stakes were positioned in the swamp to indicate the line at fire to the gunners who would be firing the gun at night. While the stakes were being positioned, the sighting crew and the battery were subject to a "tremendous fire from the enemy" for over three hours.

The gun was sighted "just to the left of St. Michaels Church" in the heart of the city of Charleston, at an elevation of 31 degrees 30. The first shells or projectiles to be fired weighed 150 pounds, not including the propellant charge that weighed an additional 20 pounds.


On the morning of August 21, General Gillmore demanded that Confederate General P. T. Beauregard, who commanded the Confederate forces protecting the city, surrender Fort Wagner. General Gillmore assured him that unless he complied, he would be forced to bombard the city. Gillmore stated in his demand "Should you refuse compliance, or should I receive no reply within four hours, I shall open fire on the city of Charleston."

General Beauregard was away inspecting fortifications when the demand arrived at his headquarters, and since no answer came in the allotted time, Gillmore intended to carry out his threat. Later in the day when Beauregard became aware of the demand he stated to one of his staff that he believed Gillmore was bluffing, adding that Gillmore's nearest batteries were "eight miles from the city."

The "SWAMP ANGEL" as the great gun had come to be known by the soldiers, lay hidden away in the tall marsh grasses "like a birds nest among the reeds," waiting to be roused from her slumber. The Swamp Angel was manned by a detachment of Colonel Plaisted's Eleventh Maine Regiment, commanded by Lieutenant Charles Sellmer. Lieutenant Sellmer was ordered to take command of the Marsh Battery by General John W. Turner, Chief of Artillery, Tenth Army Corps on August2l. He was ordered to open fire at 10:00 P.M. that evening, August 21, and was told to keep the order a secret.

Sometime in the morning of the 21st Lieutenant Sellmer started out over the plank walkway to inspect the preparations at the battery. As he walked over the trellis walkway he realized his movement was being observed by the Confederate gunners. As he walked he heard a cannon discharge from Fort Simpkins, about 1000 yards away. He could distinctly hear the shell as it whirred past his flank about 15 yards behind him. He paused for a few moments and watched. Then another gun flashed and another shell streaked across the plank walk about 15 yards in front of him. By pausing in his walk, Sellmer was able to confuse the gunners estimate of the speed of his progress along the walkway, and was able to reach the battery unharmed.

While Sellmer was returning to camp on Morris Island after inspecting the preparations at the battery, he stopped at one point, removed his pocket compass, and began taking bearings on the steeple of St. Michaels Church, which he knew was in the heart of the city.

It was not his intention to aim for St. Michaels Church, but to use it as a guide for his triangulation and trajectory calculations, since St. Michaels Church could not be seen from the battery, and the gun could not be aimed in the usual manner. This is the first known instance during the war, where a gun was aimed at an invisible object over four miles away by using a compass reading for guidance.

From about 1:00 P.M. on the afternoon of the 21st when Lieutenant Sellmer's detachment started out for the battery to man it, thirteen Confederate guns and mortars, among which were two 10-inch Columbiads, and two 10 inch seacoast mortars, fired continuously, trying to prevent the men from reaching the battery. Their firing on the battery continued non-stop all day and into the night. The enemy firing did little or no damage to the men manning them.

The mortar shells, having long time fuses, didn't explode until they had sunk into the mud, blasting huge holes in the marsh surface, which slowly filled in.

The shells from the Columbiads did not reach the battery, but burst in front of the parapet and did little damage, except for tearing up a few of the sandbags. All the enemy batteries firing on the Swamp Angel fell silent eventually, except for a few 10-inch mortars from Fort Johnson, but their firing was ineffective.

Because of the tides being not favorable, the cannon's powder charges were delayed in reaching the battery, and the original firing time of 10:00 P.M. had to be delayed.



The Swamp Angel finally opened fire for the first time on August 22, 1863, a little past midnight of the 21st making it August 22.

On the discharge of the first round, which created a tremendous low frequency bellowing thud, it was found that the design of the floating Marsh Battery, and the steep angle of fire, caused it to be very unstable, contrary to what had been expected by the engineers. At each discharge of the gun, the whole structure would rock "like a cradle" on the soft surface of the swamp, sending undulating waves across the marshland.

The first shells fired from the Swamp Angel used percussion fuses, designed to go off on impact. These shells also were one of the very first incendiary type shells fired from a cannon, and used a liquid fuel that was supposed to create a fiery explosion. The liquid used to create the fire was developed by Robert P. Parrott, the man who had invented the gun.

From the battery, no report or explosion of the shell could be heard because of the distance from the city, but after the second round, fire bells were heard and a feint reflection of fire in the direction of the city was seen by the men in the battery flickering over the wooded skyline above James Island.

The first round fired from the Swamp Angel, exploded in a street and set one house on fire. It was said that another shell had gone through the roof of St. Michaels Church and crashed into a tablet on the wall that contained the Ten Commandments, destroying all of them except two, "Thou shalt not kill," and "Thou shalt not commit adultery." St. Michaels was hit by four shells during the bombardment. Lieutenant Sellmer's aim by compass proved accurate, but at the time he opened fire he was sure the gun had been sighted to the left of the church.

Of the sixteen shells fired the first night, 12 shells were of Robert P. Parrott's design, and filled with the incendiary fluid composition he had developed. The other 4 shells were filled with an incendiary composition called "Shorts Solidified Greek Fire."

During firing, six of the incendiary rounds pre-ignited and exploded in the gun. On the 16th discharge, it was found the gun had moved nearly a yard from the epaulement, and it became necessary to cease firing. It was feared the gun might move off the platform and slide into the mud.

Though 16 rounds were fired that night, only ten reached the city, and they did little damage except to terrify the citizens who evacuated their homes to get out of the gun's range.

The following morning the assistant engineer, Colonel Serrell, inspected the damage and reported that two day's work was required to move and re-aim the gun.

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