News Stories

The Colonial-Era Cannon Mystery Continues

Published April 17, 2017
Within the enclosed tank the colonial cannon is waiting for the electrolysis process.

Within the enclosed tank the colonial cannon is waiting for the electrolysis process.

   A colonial-era cannon dredged up in the Cape Fear River has a permanent home at the Brunswick Town-Fort Anderson State Historic Site. The 8-foot long cannon, weighing between 1,000 and 2,000 pounds, was discovered Dec. 21 by workers for the Norfolk Dredging Co. The company was completing a job for the U.S. Army Corps of Engineers, Wilmington District near the boundary of the historic site and the Military Ocean Terminal Sunny Point.

   The cannon was found close to the site of the wreck of the Fortuna, one of the ships in a Spanish fleet that attacked and looted Brunswick Town in September 1748 as part of King George’s War. The Fortuna was blown up and sunk during the colonists’ counterattack. It is unclear if the cannon belonged to the Fortuna, but it has not been ruled out at this time. At the moment, staff believe the gun is either a 6 pounder or a 9 pounder naval cannon. Experts believe that the cannon was originally cast somewhere between 1690 and 1730. 

   The cannon was taken to the Brunswick Town- Fort Anderson State Historic site and initially covered with wet bags to keep the cannon from drying out.  The historic team at Brunswick Town quickly had a fiber glass tank built to submerge the cannon in water.   

   Artifacts that have been submerged for a very long time become “accustomed’ to an environment lacking oxygen.  Immediately exposing the cannon to the atmosphere before the rusting process is stopped would cause the metal to continue to erode and the gun would break apart.  Right now it is sitting in a bath water that is highly ‘basic’ (High pH number) to stop the breakdown of the metal.

   The staff is waiting for the arrival of equipment to begin the process of electrolysis.  When obtained, the cannon will be attached by wire to a battery and a ‘sacrificial’ piece of steel placed in the tank.  The electrolysis is a process in which an electric current, running through the cannon and the steel in the tank, changes both items on a molecular level.  Several different process will happen simultaneously:

   First, electricity passing through the cannon interacts with the concrete-like rust that has formed on the iron, loosening the rust, allowing it to fall off, exposing more rust.  After sitting at the bottom of the Cape Fear River for nearly three hundred years the metal absorbed salt minerals.  Electrolysis will draw the salts out of the old metal.  Finally, the electricity running through the steel creates charged molecules that travel through the wire and adhere to the cannon.  In essence, some rust material removed from the cannon is replaced by a small amount of steel.

   Depending on how much concretion, rust, and corrosion has occurred, the electrolysis process can take anywhere from three to 6 years!