Cannon Recovery

Excerpts summarized from the Report of Fort Branch Cannon Survey & Recovery Project

Underwater Archaeology Branch
Division of Archives & History
NC Department of Cultural Resources
Raleigh, NC 1979 

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Preliminary investigations determine that the many obstructions on the river bottom present a safety hazard to project participants and complicate survey and recovery activities. Attempt is made to remove as many as possible. 

Georgia Pacific Corporation delivers a 40 x 100 ft. barge to the site on loan for the project which will become a staging area for underwater work. A stairway is constructed from the top of the bluff providing access for equipment delivery such as scuba gear, compressors, temporary storage tanks for artifacts and airlifts. 
 

The search area is approximately 90 x 110 feet and is divided into a grid of 18 five-foot-wide search lanes running parallel to the river bank. Each lane is systematically searched. Lack of visibility proves to be a serious limitation in dealing with artifacts submerged beneath as much as one foot of sediment and others hidden among debris and obstructions. Tactile examination and use of underwater metal detectors are essential. A tedious location, cataloguing, tagging and removal system is followed. Artifacts are placed into temporary wet storage on the barge and later transferred to secure storage in the project camp at the top of the bluff where they were photographed. 

In addition to the grid area, another area was determined to contain the largest concentration of smaller artifacts. Among other items, two brass cannon sights are discovered here. 

Once lanes containing cannon is cleared of artifacts and surface obstructions, a second operation begins. Using airlifts, additional crews begin excavation in the vicinity of the cannon. This excavation serves two purposes: to clear sediment from the guns so lifting straps can be secured and to locate artifacts obscured from the metal detectors by masking the effect of the iron cannon. In addition to the two large cannon, three cannon carriages are found in bottom sediment. Tons of mud and sand must be air lifted away before these pieces can be positively identified and prepared for recovery.

Exposing the carriages reveals that two would mount what is identified as 6-pounder field pieces. The third is an empty siege and garrison carriage similar to the one recovered in 1972. Sediment continually refills the bottom of the sizable depression where the fieldpieces and empty carriage are located. The small cannon and carriage are slung with lifting straps and attached to sunken 55-gallon drums. The drums are filled with air, lifting the items to the surface where they are moved to more stable bottom before being raised during the recovery operation. Large wheel rims are treated in the same manner. This further clears the area surrounding the large cannon.

 Unrelated to this project, the US Army Corps of Engineers’ snag boat SNELL works its way up the Roanoke removing trees and debris to clear river for navigation. Underwater Archaeology Branch requests their help. Three days were scheduled for the SNELL & its crew to assist in the clearing effort. Divers locate snags with a recording fathometer and cable each one for removal by the SNELL. Before lifting, each snag is carefully examined by divers to ensure that any material that may have been thrown into the river from the fort is not disturbed. In spite of the care taken, the first snag brings with it a wood and iron wheel rim. The rim is immediately retrieved but snagging operations are discontinued in that area. Obstructions are removed from the area below Fort Branch.

Less than two months after the snagging operations, the survey and recovery project begins. First objective is a comprehensive topographic survey of site. This would generate data for compilation of a topographic map as well as establish controls essential for production of magnetic profiles of the site, bathymetric profiles, and the systematic recovery of material from the river. Survey crews, working in temperatures often exceeding 100 degrees Fahrenheit, establish baseline coordinates from through the length of the earthworks and place stakes at 20-foot intervals throughout the site. These grid lines are carried over the bluff to the water’s edge and continued across the river to establish points along the north bank so that location of material and data removed from the river bottom can be coordinated with the survey of the fort. Since Rainbow Banks is nearly vertical, profiling the bluff requires geometric survey techniques rather than conventional.

After survey markers are established on both banks, magnetic and bathymetric profiles of the river are conducted. From a small boat positioned by lines stretched along the survey lanes running across the river, water depth and magnetic data is collected every 20 feet. A small recording fathometer determines water depth and a Geometrics (801-G) proton precession magnetomer measured magnetic gradient. These data are plotted on a site map and correlated with the topographic map of the fort. The information indicates a concentration of ferrous material below the bluff west of the original entrance to the fort….where preliminary investigations located cannon and gun carriage remains. Researchers make final preparations for diving, excavation and recovery operations.

The Army Reserve LCU 1476 arrives with a 20-ton capacity mobile crane. Twenty-thousand pound capacity nylon straps are provided by the US Army for slinging guns. The fabric straps are stronger than rope or even steel cable and will not chafe or cut into the metal surface of the cannon.  

With all items prepared for recovery and the crane on site and ready, a final briefing session is held at 7:30 a.m. to insure coordination and a clear understanding of the entire operation. Law enforcement was on hand to provide crowd control (the operation attracted much curiosity and interest) and safety. River traffic was appraised of the planned activities and the operation was ready to begin. 

With the cannon already slung, diving operations required only the hook of the crane be attached to the lifting straps with a final check to be certain they were secure. As the crane cleared the river bottom, a projectile was discovered under the carriage! With no way of knowing whether it was live, the operation was halted until the projectile could be carefully removed and carried to the surface by a standby safety diver. 

The gun is lifted to the surface, straps are inspected, and it is gently swung onto the LCU and positioned onto automobile tires and oak blocks. The gun is a 24-pound smoothbore Model 1819 on wooden siege and garrison carriage. Once aboard the LCU a continuous mist of fresh water is sprayed over it to slow further deterioration. A complete photo documentation is begun. 

Divers return to the river for one of the 6-pounder fieldpieces. It is much lighter but requires even more care because a portion of the wheel carriage is intact. Tires and oak blocks are positioned so that no weight is placed on the fragile wheel carriage once it is set onto the LCU. Again, a continuous freshwater mist is used.

Once secured, the LCU heads upriver for the boat landing at Hamilton. The cannon are removed onto a trailer provided by the North Carolina Department of Transportation (DOT) and returned to Fort Branch. Public access is possible during documentation and disassembly due to a sprinkler system set up in an open area near the top of the bluff from which the guns were pushed 112 years earlier.