This was spurred by the Spanish–American War and included tunnels and gun emplacements, with the fort enlarged until 1902. The first of Fort Greble's works was Battery Hale, completed in 1897 with the emplacement of three 10-inch M1888 disappearing guns. A battery was constructed for one 6-inch Armstrong gun shortly after the war started, but the gun was removed in 1903.
Fort Greble's fortifications were built in response to the Spanish-American War, including tunnels and gun emplacements.