During the Mexican War, the fort was used as a recruitment and training facility. Fort Johnston was part of the Cape Fear Defense System during the Civil War, and contributed to the Confederate protection of Fort Fisher. On Feb. 21, 1881, the U.S. government ended Fort Johnston’s role as a seacoast defense. But, the grounds were still useful. From June 1881 through the present day the fort’s buildings have been variously used by the U.S. Signal Corps, the Weather Bureau, the U.S. Army Corps of Engineers and the U.S. Surveying Corps. The fort was officially given to the City of Southport in 2006.
On the grounds of Fort Johnston today, Cannon Thor can be seen. It is nicknamed Thor from the mythical god of thunder. It is Southport's full-size replica of a 1841 bronze 6-pound cannon. in May of 1991, Cannon Ltd. of Coolville, Ohio built the cannon for Robert C. DeHaven. Thor can be seen in Ted Turner's film Gods and Generals. DeHaven then gave it to the Southport Historical Society to be used during special events in Southport, most notably Southport's famous Fourth of July celebration and parade.
Every summer the people of Southport prepare for the biggest celebration of the year - The Forth of July Festival. They have been putting together the festival for over 200 years. The celebration has grown from colonial times when ships lay anchor in her harbor and shot their cannons to today's festival where 40,000 to 50,000 people come each year from all over to take part in the festivities. The town's people put together games, entertainment, arts and crafts displays, a parade, and fireworks to end the day. It was incorporated as the N.C. 4th of July Festival in the year 1972.