Fort Macon Moat
by: Paul Branch, Ranger
Most visitors to Fort Macon are interested in the moat, the sunken area that separates the outer and inner walls of the fort. From childhood tales of medieval knights and castles, visitors do have a degree of familiarity about moats when they see a real one at Fort Macon. The most typical questions about it are: “Was there water in there?” and “Did they keep alligators in there?” The answers are Yes and No, respectively. But there is more to the story of the moat and what follows is an examination of the role the moat plays in Fort Macon’s defense.
In the science of fortifications, the wide, deep sunken area around a fortification, or separating the defensive areas of a fortification, is properly known as the Ditch. Its purpose is to provide an obstacle to an enemy ground assault and prevent the fortification from being easily overrun. If the ditch is made to be flooded with water to provide additional troubles for the enemy, it will become a “wet ditch” or “moat.” When a fortification is constructed, the earth excavated from the ditch is thrown outward to form the earthen slopes of the parapet or glacis in front of the fortification. The ditch must be sufficiently wide and deep so that an enemy assault force cannot easily cross it during an attack by filling it up with earth, stones, logs or other materials at hand to make a bridge. Similarly, if the fort or castle’s wall is collapsed by artillery fire, the ditch’s width and depth must be sufficient to prevent being filled with rubble to provide a ramp for an assault force to get across to the inside. In many fortifications, including Fort Macon, defensive galleries are provided to halt enemy incursions into the ditch with rifle and artillery fire. In the case of Fort Macon, these “counterfire galleries,” four in number, are located in the angles under the outer wall and could direct defensive gunfire down all five avenues of the ditch. Thus the ditch becomes a trap where enemy soldiers trying to cross the ditch become bogged down and slaughtered in a crossfire.
Access across the ditch from the outer wall to the inner citadel for Fort Macon’s garrison was provided by wooden bridges at the main sally port and postern. The original plans for the fort called for these to be draw bridges that could be lifted up to prevent their use by the enemy during an assault. When the fort was built, however, no draw bridges were installed and only stationary wooden bridges were provided. Of course, these could be quickly destroyed by the garrison if necessary to prevent their use by enemy storming parties.
Fort Macon’s ditch as it appears today is not the same depth as when the fort was first built. Originally it was three feet deeper than it is today, fixed at the level of mean low water. Water to flood the ditch was provided by an enclosed masonry culvert through the outer wall that entered the ditch beside the north counterfire gallery. The culvert was about 120 feet long and extended under and beyond the earthen slope (glacis) of the outer wall. Outside the fort, water was conducted to the exterior opening of the culvert by an open brick-lined channel extending northwest of the fort to the marshy areas comprising the headwaters of nearby Cowpen Creek (now the Coast Guard’s boat basin). Tidal water from the mashes and creek flowed through the channel and culvert to flood the fort ditch.
In the years following the fort’s completion, the flooding in the ditch proved to be very difficult to regulate. High water levels in the ditch from storm tides kept the counterfire galleries flooded to the point they were useless for defense. Of course, the pungent water standing in the ditch was a source of mosquitos to plague the soldiers. During the fort’s construction two valve gates at each end of the culvert were intended to control the flow of water but it does not appear they were ever installed since an engineer inspection report from Captain Robert E. Lee in 1841 recommended the installation of a gate to control the flooding. Continued problems regulating water in the ditch led army engineers to fill it in and raise its level by two feet in 1843. While this minimized its effectiveness as a moat it apparently was sufficient to control some of the flooding.
In 1898 during the Spanish-American War a further change was made to the ditch when a shell magazine for a battery of mortars at the south angle of the outer was established in the south counterfire gallery. To prevent water in the ditch from causing a problem for the ammunition in the magazine, the army engineers filled in the ditch yet another foot and then dug a drainage trench through the center all the way around. During the 1934-35 Civilian Conservation Corps restoration of the fort, the drainage trench was filled in, leaving the ditch at its current level. In the 1930s and during World War II, the marshy area between the fort and Coast Guard Station was filled in. The old channel from the marsh to the outer end of the culvert leading under the outer wall into the ditch was covered over. There is no trace of the channel or culvert opening today. The culvert itself still exists, however.