From the 2015-2016 Coaster Magazine.
These mysterious towers are located along Topsail Island, North Carolina and are a great conversation piece for first-time visitors. Even long-time residents often are not sure. Perhaps they were World War II U-boat spotting towers (as many Allied merchant ships were sunk off the North Carolina Coast in the Battle of the Atlantic). maybe they were used to spot whales?
Topsail island was separate from the mainland until the 1940s, only reachable by the few locals who knew how to make their way through the marsh at low tide.
These towers played a huge role in the history of the United States military.
It was the U.S. Army that first came to the Topsail area. In the space of six months during World War II, the government constructed Camp Davis nearby on the mainland at Holly Ridge. Troops training and based there could conduct artillery training in the remote area.
At the end of the war, much of the base was dismantled and the troops transferred.
It did not take long for the U.S. Navy to take note of the island's possibility and they put it to use.