A position on the marsh for a battery: An engineering challenge

If there is one aspect of the operations on Morris Island that gives the “Glory Charge” a contest in terms of recognition, it is the Swamp Angel.

Trenton 14 Aug 10 382

Before I go into the story of this famous gun, I must mention the engineering required to put the gun in position and, for a start, the story of the site selection for the battery.

After the first assault on Battery Wagner, Brigadier-General Quincy Gillmore directed his engineers to determine if any locations in the marsh behind Morris Island might sustain a heavy gun battery. Gillmore was not asking for a position to fire on Charleston at that time. Rather he desired a position somewhere to the left of the siege lines which might offer a fresh angle on Fort Sumter.

The task went to Colonel Edward Serrell, First New York Engineers. On July 16 he went out into the marsh on foot, accompanied by Lieutenant Nathaniel Edwards, searching for any patch of high ground, relatively speaking, in the marsh. Later that day, Serrell forwarded his report (sent to Major Thomas Brooks, Assistant Engineer to Gillmore):

I have the honor to report that, agreeably to the orders of the general commanding the department, I made this morning, assisted by Lieut. N.M. Edwards, Volunteer Engineers, a reconnaissance across the marsh, from the batteries on our left to the creek between this island and Light-House Creek, a distance of about half a mile, bearing, from the southwesterly end of the.hard ground, a course by magnetic compass north 40° west, to a point from which the bearing to Fort Sumter is north 12 east, and to the old beacon light south 89° east. At this point there is a spot of hard ground a few inches above or below high-water mark, irregular, from 25 to 30 feet long, and 15 to 18 feet wide, the longer axis being perpendicular to the fire of Fort Sumter, or nearly so. Between this spot and the hard ground on which the batteries are now being built, the marsh may be crossed by infantry at low tide, with some difficulty. About one-third of the distance will bear a man, sinking in 1 or 2 inches, another third, 6 or 8 inches, the other third, somewhat deeper.

Again, notice the report focused on the angle at which fires would fall on Fort Sumter, not Charleston. The position Serrell examined online with the Left Breaching batteries (and a good bit back of where the Swamp Angel battery was later placed).

Serrell continued in the report to offer suggestions as to how to build a battery in the marsh:

A battery to be constructed at this point must be entirely made of sand-bags, with platforms grillaged.

I think a gun weighing not over 10,000 pounds can be drawn across the marsh on skids framed together to slip on the mud, similar to those used by General Bonaparte for crossing the Alps on the snow.

Two thousand three hundred men can carry filled sand-bags enough, in one night, to make the battery and cover the magazine, if they are well organized. Sixty more can carry the platform across and put it down, including the grillage. It will require about 400 or 450 more men to put the guns in position the next night.

The skid should have a bearing surface equal to 90 or 100 square feet.

One small creek, about 9 feet wide, will have to be crossed. Two or three logs put over it will be sufficient.

Thirty-five additional men can carry the magazine and put it up.

The work can be done better in daylight than dark, excepting that it may draw the fire of the enemy.

Yes, one cannot escape the references to Napoleon. If Serrell’s plan worked, the battery just “appear” within a day or two. But that was not to be. Instead, the engineers continued to examine locations in the marshes that would support heavy guns, given some engineering work. After a couple weeks of examinations, the engineers had mapped out several possible locations.

But Gillmore did not issue orders to build a battery until August 2nd (on or about). Serrell related:

The commanding general having ordered that the work should be made suitable for one 200-pounder Parrott rifled gun, and that it should be placed as near to the city of Charleston as practicable, on our side, however, of the stream next southeasterly from Light-House Creek, it became evident that whatever details of plan might be adopted, the general features of the localities being similar, the primary arrangement would remain constant, wherever the position might be finally determined upon.

The location Serrell selected was advanced far forward of the other Federal works (indicated below with an orange box):

MorrisIslandJuly28

From his own report, Serrell indicated several suitable sites were located, from which he selected the most convenient for the directed purpose. By that time, in early August, Gillmore had a different target in mind – the city of Charleston itself.

(Citation from Serrell’s report, OR, Series I, Volume 28, Part I, Serial 46, pages 230-1.)

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3 responses to “A position on the marsh for a battery: An engineering challenge

  1. Pingback: 150 years ago: Colonel Serrell probing the marsh | To the Sound of the Guns

  2. Pingback: 8,800 days’ worth of work: Constructing the Marsh Battery | To the Sound of the Guns

  3. Pingback: 150 years ago: “The Swamp Angel broods in his gloom” | To the Sound of the Guns

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