Guardian of the Gulf

Fort Jefferson, the largest all-masonry fort in the United States, was built between 1846 and 1875 to protect the nation's gateway to the Gulf of Mexico. Supply and subsidence problems and the Civil War delayed construction, and sections of the fort were intentionally never completed because of fears that additional weight would cause further settling and cracking. It illustrates the pinnacle of masonry fort architecture and engineering in the United States and features nearly 2,000 arches. Time, weather, and water continue to take their toll, requiring ongoing stabilization and restoration projects. The moat wall, called the counterscarp, protected the fort’s main walls from battering waves and prevented enemy ships from reaching the scarp. After Florida left the Union in 1861, the red bricks along the top of the fort’s walls were shipped from Maine, nearly 2,000 miles away, while the original tan bricks on the lower two tiers came from brickyards near Pensacola before Florida seceded from the Union. Overall, 16 million bricks were used. Built-in recessed sections called blind embrasures looked like additional gun ports from a distance, and corbeled arches formed a ledge that helped prevent rainwater from running down the face of the fort. Wrought-iron Totten shutters opened when guns were fired and closed automatically between shots to protect the cannon and gun crews, but the iron rusted in the salt air, expanded, and pushed the bricks apart. A program to replace the shutters with composite replicas began in 2002.