At the eastern end of Perdido Key is an area once used by the U.S. Army to defend Pensacola Bay. A three-tiered fort with a detached water battery called Fort McRee was built there between 1834 and 1839. During the Civil War, the fort was heavily damaged in a massive artillery exchange between Confederate forces at McRee and Barrancas, and Union forces at Fort Pickens and onboard the ships Niagara and Richmond in November 1861. Coastal erosion crumbled the foundations afterward, and by the 1906 Hurricane destroyed Fort McRee. All that was left was a single arch that eventually eroded away.
The end of the island was still called Fort McRee, and concrete Coast Artillery batteries were built there in 1899, 1900 and 1942. Battery 233 was the last built and remains today. Access is by 4x4 vehicle or by foot.