The first cannon pulled up from Georgia’s Savannah River surprised the workers for the Army Corps of Engineers who dredged them out of the riverbed’s clay.
The next two piqued their interest, and brought divers, archaeologists and sonar operators to search for more centuries-old treasures.
Then they pulled up 12 more cannons, covered in rust, sediment and mussels, and when experts began to lecture about the discoveries, they didn’t even know that yet another cannon had been found.
By the time the dredging project ended in March, the corps had brought 19 cannons to the surface, all thought to be relics from ships sunk during the American Revolution, when the British occupied Savannah.
Andrea Farmer, an archaeologist for the Savannah district of the Army Corps of Engineers, said the cannons were most likely from the HMS Savannah, one of several British vessels sunk in an area called Five Fathom Hole. The Savannah was sunk to block the advance of French troops, who were allied with the rebels, in September 1779.
“There are historical records from the time period that state it was sunk so quickly that they left everything: the armament, the provisions, pretty much the only thing that was not on board were humans,” Ms. Farmer said.
By the fall of 1779, George Washington was trying to organize an offensive against the British along with the revolutionaries’ French allies. That October, American and French forces assaulted the city of Savannah by land in one of the deadliest battles of the war, known as the Siege of Savannah. But they failed to dislodge the British, and the French fleet sailed for home before the start of hurricane season. The British didn’t evacuate Savannah until years later, in 1782.
“Savannah would honestly look a lot different today if they had been able to attack via the water,” Ms. Farmer said.
Several entities have an interest in the future of the cannons, including the federal government, the British government and the state of Georgia, which owns the water where the cannons were found. Ms. Farmer said that the groups were working on an agreement to keep the cannons in Savannah, ideally on display at the Savannah History Museum, and aimed toward a window that overlooks the location of the 1779 battle.
The Army Corps of Engineers found the first cannon in February 2021, as it worked on a $973 million project to deepen a 40-mile stretch of the Savannah River. The engineers had to temporarily stop dredging after they found the first three cannons, and they brought in sonar equipment and divers to search for and recover the others buried under the sediment.
Conditions did not cooperate. Divers worked with little to no visibility in the river water, and sonar failed to detect the last of the cannons — which were found only after dredging resumed this year.
To date the cannons, researchers considered their size and looked at structural details such as the placement of trunnions and bolts, hoping to figure out where they were made and compare them to existing weapons records.
Ms. Farmer said that they initially thought the first cannon might have been from a sunken Civil War ship, the C.S.S. Georgia. That seemed less likely after the two other cannons were found, because the corps had already done an extensive excavation of that wreck. Researchers who examined the cannons later confirmed that the guns were not from that ship.
Ms. Farmer said at least four of the cannons were 70 inches long and were “more than likely” manufactured in France. The other 15 are about 60 inches long and were built for heavy use, but researchers have not been able to find similar cannons in any historical records. “This story is very much still developing, there is still a lot to learn from the artifacts and through the conservation process,” Ms. Farmer said.
For now, the cannons are sitting in troughs lined with plastic and filled with fresh water, to better preserve them until they are sent to a conservation lab. Unexploded ordinance technicians have also confirmed that the cannons are not a safety concern, though the water baths provide an extra layer of protection.
In its construction projects around the world, the Army Corps of Engineers has a long history of uncovering artifacts.
In 2009, during a dredging operation, the Galveston District brought a 10,000-pound Civil War cannon to the surface from the Texas City Channel. A paleontologist with the corps and an Air Force archaeologist found ancient hand axes while on a surveying trip to Niger in 2017.
Drawing on its expertise, the corps also created a program in 2009 for military veterans to process the many artifacts, such as pottery shards and stone tools, that it has collected over its many decades of infrastructure projects.