CSS Georgia

Project Sponsors
The site was excavated in 2015 and 2017 under the direction of the US Army Corps of Engineers (USACE) and the Naval History and Heritage Command (NHHC) Underwater Archaeology Branch (UA) as part of the Savannah Harbor Expansion Project. The ship is owned by the US Navy and is currently under the stewardship of the NHHC-UAB.

Time period: 1863-1864 (American Civil War)

Site History and Fieldwork

CSS Georgia was a Confederate ironclad built in Savannah, Georgia with the funds raised by the Ladies’ Gunboat Association. Georgia was intended to protect the port, but the steam engines lacked the power for offensive use, and so was anchored in the Savannah River, near Old Fort Jackson, as a floating battery. Though successful as a deterrent, CSS Georgia was scuttled in December 1864 to prevent capture by General Sherman.

The location of the site–in the middle of a busy shipping channel, with little to no visibility in the water–meant that it would be too dangerous to conduct a traditional underwater excavation with divers. Instead, a barge crane was outfitted with: a transponder (to allow archaeologists to map the site using GIS), a grapple (for large artifacts, like pieces of the casemate), and a clamshell (for smaller artifacts). Archaeologists and CRL staff excavated each “grab” on the deck of the barge and determined which artifacts would be sent to the CRL for conservation. This method was more effective than expected: even artifacts as small and delicate as a wood domino and ceramic pipe bowl were recovered safely.

Ammunition Box

This box and its contents remained together due to the concretion that formed inside and around the box. Each round shot and its respective sabot was removed from the box using an air scribe and numbered to preserve their order and placement, and then the box disassembled using hand tools.

The iron shot was conserved using electrolytic reduction, then coated with tannic acid and sealed with microcrystalline wax. Conservators removed the very corroded iron nails from the wood before dehydrating them in baths of organic solvents and treating them using the silicone oil process developed at CRL. For reconstruction of the box, conservators created replacement nails, made of epoxy, based on the original nails. This allows for the box to be displayed as intact as possible, without re-introducing iron that could begin to corrode again.

Although putting the shot and sabots together in the box makes for some great photos, for transportation and long-term storage, all of the components were packed separately.

Railroad Iron

Lacking rolled iron plate that, in combination with oak and pine timbers, would normally be used to construct the vessel’s casemate (the protective covering above the waterline), CSS Georgia’s builders utilized railroad iron. The railroad iron was rotated to interlock with other pieces of rail, and held together with mortar. Long iron fasteners attached them to the timbers underneath.

The CRL conserved a representative sample of the casemate components. The fact that the longest rails recovered were about 24 feet in length meant CRL had to construct large tanks just to hold them. In order to fully conserve the iron, conservators used air scribes to remove concretion, then separated any connected sections, removing any mortar holding the rails together to be desalinated and conserved separately. The iron was conserved using electrolytic reduction and sealed using microcrystalline wax and black alkyd paint.

In 2017, large sections of the casemate were lifted from the Savannah River. These were thoroughly photographed in order to create orthomosaics, a form of digital documentation that allows for researchers to more easily study such massive artifacts.

Native American Ceramics

Nearly a quarter of the collection is identified as Native American ceramics. Although the assemblage has not been fully analyzed yet, a cursory examination indicates it “represents prehistoric types dating from the Woodland through the Mississippian periods and possibly into the Historic period” (Panamerican Consultants 2020: 244). The decorated sherds show a variety of techniques including “cord-marked, check-stamped, punctate, incised, and complicated designs” (Panamerican Consultants 2020: 244). The sherds, mostly small fragments, were located throughout the site of CSS Georgia, with a slight concentration to the northern side.

Why is there such a concentration of prehistoric ceramics in a Civil War site? The presence of pre-Civil War artifacts is not surprising: the Savannah River has been used for shipping traffic for a long time, and there are also artifacts like buttons and bottles recovered from the site that date closer to the Revolutionary War period than the Civil War. It is the large number of sherds that is odd. This may indicate that there was once a Native American settlement nearby; alternatively, past dredging and construction activity along the Savannah River may have caused the sherds to wash downstream, and this part of the river, and later CSS Georgia, acted as a catchment.

In the field, the sherds were all almost uniformly black from long immersion in the river’s mud. Under the black color, conservators found they were also rust-stained from long exposure to the iron of CSS Georgia. After desalinating the sherds, conservators immersed them in baths of hydrogen peroxide in water to remove the dark organic staining, and baths of oxalic acid in water to remove the iron staining. After being thoroughly washed to remove the chemicals and air dried, they were immersed in a 3% solution of Acryloid B-72 in acetone to consolidate and seal them.

IX-inch Dahlgren Cannon

Dahlgren guns are named for Rear Admiral John A. Dahlgren who, after witnessing an accidental explosion of a gun being tested for accuracy, set out to design a safer, more powerful naval cannon. These muzzle-loading smoothbore guns are characterized by a smooth curved shape, with more weight in the breech, giving the guns a soda bottle appearance.

A total of 1,185 IX-inch guns were cast between 1855 and 1864 at seven foundries, including Tredegar Iron Works (the biggest ironworks in the Confederacy during the American Civil War), which is where this particular gun was cast in 1862. We know this because of the markings on the trunnions: “1862” on the left and “JR[pitting] TF” on the right. JRA were the initials of the owner of Tredegar Iron Works, Joseph Reid Anderson.

Two Dahlgrens were recovered from the site of CSS Georgia, but this particular gun stood out during excavation and conservation. First, it wasn’t detected during magnetometer surveys since it was obscured by the casemate, so it was quite a surprise when the crane deposited it on the barge’s deck. Second, at CRL we found that the bore was obstructed not just by concretion, but by a grapeshot stand with an octagonal wood cannister, and a shell with a wood sabot, all placed backward down the bore—likely to prevent it from being used by Union forces in the event the gun was salvaged.

Conservators began electrolytic reduction while the bore was still blocked in order to help loosen the concretion and the contents within. During each solution changeout, the bore was mechanically cleaned until it was clear. All of the items listed above were cleaned of concretion and conserved separately.

Roller Handspike

The Marsilly carriages that carried the two Dahlgren guns were designed without rear trucks (wheels), which increased the friction between the carriage and deck, and prevented additional movement of the Dahlgren cannons when they were fired. Roller handspikes were used as a lever to raise the back to allow for the carriage to run in and out, rotate, and be trained.

The roller handspike, like most tools used for guns and carriages, is a tool set at one end of a long, wood pole. Most of the wood on this artifact has degraded away, leaving just a couple fragments of the pole as well as the roller, which had two brass bushings (one inserted on either end), and an iron pin that attached the roller to the brass spike and reinforcement. The spike was disassembled so that all components could be conserved separately: the wood components were conserved using silicone oil, and the brass and iron were treated using electrolytic reduction.

Conservators at work on CSS Georgia artifacts

External Resources

From Ironclad to Artifact: The Journey of the CSS Georgia. (This is the official U.S. Army Corps of Engineers documentary on Georgia, filmed by Michael Jordan of Cosmos Mariner Productions.)

USACE Savannah District Information

The most comprehensive source about the survey and excavation of the site of CSS Georgia, including an overview and analysis of the artifacts, is the 2020 official report CSS Georgia Archeological Data Recovery and Mitigation for the Savannah Harbor Expansion Project (SHEP), Chatham County, Georgia and Jasper County, South Carolina.