Trapped in a deadly machine called the deep-sea sailing ship, sailors who turned pirate fought a furious battle for survival. Any given pirate ship might have English, Irish, Greek, Dutch, French, or Native American crew members. The social composition of the pirate ship proved the point, as did the parrot on the pirate’s shoulder. Yet the flag also bespoke the pirates’ own fear of being preyed upon in turn. Marcus Rediker is Distinguished Professor of Atlantic History at the University of Pittsburgh.