Fort De Soto was never meant to stand alone. It was one half of a two-fort system designed to seal the mouth of Tampa Bay, and the other half was Fort Dade, across the channel on Egmont Key. Where Fort De Soto held the high-angle mortars that dropped shells onto a ship's deck, Fort Dade held the long-range guns that could reach far out to sea, and the two were meant to fire together, their fields of fire crossing over the deep-water entrance. To understand one fort is to understand the pair.
Fort Dade was named in the very same War Department order, General Orders No. 43 of 4 April 1900, that gave Fort De Soto its name. Its namesake was Major Francis L. Dade of the 4th U.S. Infantry, killed with nearly his entire command in an ambush by Seminole warriors on 28 December 1835, the event remembered as the Dade Massacre that opened the Second Seminole War. The irony sits heavily on the island: Egmont Key had served, only a generation before the fort was built, as an internment camp for captured Seminoles being shipped west. The Army put the name of the man whose death began the Seminole wars onto an island that had been a waystation in the removal those wars produced.
Fort Dade's armament made it the heavy-hitting, long-range partner in the system. Its principal batteries, recorded in detail by the Coast Defense Study Group, were Battery McIntosh, with two 8-inch guns on disappearing carriages; Battery Howard, with two 6-inch guns, also on disappearing carriages; Battery Burchsted, with two 6-inch Armstrong guns on barbette mounts and a 3-inch gun; Battery Mellon, with three 3-inch guns; and Battery Page, with two 3-inch guns. Disappearing carriages let a gun rise to fire, then drop back behind its parapet to reload out of sight, the most modern coastal-defense technology of the age. Together with Fort De Soto's mortars and the lighter guns covering the channels between the islands, they formed what the engineers intended as a complete coast-defense complex.
One piece of Fort Dade's armament still has a public life, and most who see it do not know its origin. The two 6-inch Armstrong guns now displayed at Fort De Soto are not original Fort De Soto weapons at all. They came from Fort Dade's Battery Burchsted, salvaged and carried across the bay in 1980 to be displayed and to help tell the story of the larger Tampa Bay defenses. Fort De Soto's own original guns were Battery Laidley's mortars and Battery Bigelow's rapid-fire guns; the Armstrong guns are transplants from the sister fort.
Like Fort De Soto, Fort Dade was far more than its batteries. It grew into a self-contained community of more than seventy buildings and some three hundred residents, with brick streets, a narrow-gauge railroad, electric light, a hospital, a jail, a movie theater, a bowling alley, and tennis courts, a small American town set down on a barrier island. It was deactivated in 1923 and briefly pressed back into service during the Second World War.
Today Fort Dade is a ruin, and a shrinking one. Three of its batteries survive on the island as weathered concrete, but erosion has been merciless: Batteries McIntosh and Howard now stand in the water, awash offshore, and the brick streets of the old town run down into the surf and stop. The island is a state park and wildlife refuge, much visited by boat, a genuine ghost town slowly going under. It is the clearest possible illustration of the fate that erosion has already begun to deal Fort De Soto's own lost Battery Bigelow, and that the Gulf holds in store for these keys.