Privateer

A privateer is a ship, not unlike a pirate ship, that attacks and plunders other vessels. The most fundamental difference is that a privateer actually works on the orders of a Government - they go out, without insignia (so for which country they work cannot be proved) and attack the ships of rival or enemy nations. The most famour privateers were those of the English at the time of the Spanish Armada, and Francis Drake in particular. They would attack Spanish ships returning from South America and steal the gold and treasure onboard.