Fort Zachary Taylor at the southern end of Key West grew from an antebellum coastal defense project into one of the island’s most important military sites. Begun in 1845 on a strategic position selected to guard approaches to the southeastern United States, the massive brick fort was built slowly with enslaved labor under difficult conditions and reshaped Key West during construction. In January 1861, Captain John Milton Brannan secured it for the Union before Florida’s secession took full effect, and it became a key post against blockade runners. Later modernized and reused in several wars, it eventually became a Florida state park and National Historic Landmark.