Well, that's one I never heard about. So I stopped. Turns out that this was a Spanish fort started in the early 1700s. And when the British showed up and tried to take it away from them, well, they couldn't. In fact, they did so badly it was more of a slaughter than a battle, hence the name which means massacre. After a brief film in the visitor center I moved outside to the dock to wait for my ferry over to the fort.
After returning to the mainland I walked the nature trail in hopes of seeing a little more of the local denizens with no luck. Did find this old marker in the woods although no one really knows exactly where the actual massacre took place.
All in all a great way to spend the morning. Oh, and the total cost was $0000. What a bargain!