06/18/2026
On June 15, 1569, Fort Anton de Carlos was abandoned.
Built by the Spanish on Mound Key in 1566, the fort reflected the troubled and temporary alliance between the Spanish and the Calusa, the most powerful Native American tribe in southwest Florida. A series of attacks and reprisals by both sides ultimately resulted in the island’s abandonment by the Calusa and the Spanish not long after.
The Calusa would nonetheless demonstrate a resiliency not often matched by other southeastern tribal societies and continue to exist into the 18th century.
To learn more about the archaeology that revealed Fort Anton de Carlos, visit https://www.floridamuseum.ufl.edu/science/spanish-fort-on-mound-key/ or check out the new local history collection at Mid-County Regional Library for a selection of books on the Calusa and the Spanish period in Florida.