Privateers were little more than legal pirates, and legal only because the monarch gave them written permission to raid the ships of specific rival powers. To protect against a breech of the terms contained in these letters of marque, privateer captains—who were not naval officers and did not take orders from the naval command—would often be required to post a bond or accept liability
for damages if they should go above and beyond the terms of the letter.

This legal framework made privateering into a business, just like any other. Many ships were outfitted with the money from investors who were seeking a return on that investment from captured gold and merchandise. Others saw it as doing their part against the nation’s enemies.

The types of ships used in privateering were many and various, ranging in size and power from schooners to sporting a couple of cannons small frigates. Their crews also ran the spectrum from ex-naval seamen and officers to experienced merchant seamen to criminals and debtors of various stripes. It was also not unheard of for legitimate privateers to become pirates. One famous example of this is Captain William Kidd, who began his career as a privateer but was later hanged as a pirate.