But why? The Bahamian pirates were unlike most other pirates who’ve come before or since in that they claimed to be engaged in more than simple banditry. Most, including Blackbeard, were former merchant and naval sailors who thought themselves engaged in a social revolt against shipowners and captains who’d made their lives miserable. The pirate Sam Bellamy’s crew referred to themselves as Robin Hood’s men. “They vilify us, the scoundrels do, when there is only this difference,” Bellamy told a captive. “They rob the poor under the cover of law” and “we plunder the rich under the cover of our own courage.”

There was also a democratic spirit aboard the pirates’ ships six decades before Lexington and Yorktown, more than seven ahead of the storming of the Bastille. Upon seizing a vessel, the pirates turned its government upside down. Instead of using whips and beatings to enforce a rigid, top-down hierarchy, they elected and deposed their captains by popular vote. They shared their treasure almost equally and on most ships didn’t allow the captain his own cabin. The contracts some crews drew up and signed included disability benefits: payments for lost eyes and limbs taken from the shared plunder before it was divvied up.

All this — and far better food, drink and hours — made piracy extremely attractive to merchant and naval sailors alike, who in this time period faced malnourishment, wage cheating, and brutal and sometimes sadistic officers. Typically when the pirates captured a ship, a portion of its crew would enthusiastically join their ranks, allowing the outbreak to expand from a handful of pirates in sloops to several thousand in multi-ship squadrons in just three years. Even the Royal Navy was vulnerable; when the ship H.M.S. Phoenix confronted the pirates at their Nassau lair 300 years ago this spring, a number of the frigate’s sailors sneaked off in the night to serve under the black flag.

Runaway slaves also joined the pirates as word spread that they allowed people of African descent to participate as equal members of their crews and sometimes as captains. At the height of the outbreak, it was not unusual for escaped or liberated slaves to account for a quarter or more of the pirates’ crews. In the months after Blackbeard captured his flagship, Queen Anne’s Revenge, witnesses would report as many as 70 serving aboard, and several remained in his closest circle to the day he died. Although pirates also treated many of the slaves they found on captured slave ships as cargo to be sold, not colleagues to recruit, their integrated ships still represented a threat to the slave colonies surrounding the Bahamas. Gov. Benjamin Bennett of Bermuda warned that slaves had “grown so impudent and insulting of late that we have reason to suspect their rising” against us and “fear their joining with the pirates.”

Not all pirates were downtrodden. Bellamy’s sidekick Paulsgrave Williams was the son of Rhode Island’s attorney general, and the “gentleman pirate” Stede Bonnet was the scion of an influential Barbados family. There’s considerable evidence that these pirates had a secret motivation of their own: to depose George I — who had ascended to the throne in 1714 — and restore the Stuarts. Some of the pirates sent a letter to the court of the would-be Stuart king in exile in France offering their services, while several others were closely associated with a suspected organizer of a failed, pro-Stuart uprising in 1715.