During the 16th and 17th centuries, English privateers patrolled the seas, raiding and plundering foreign ships. Unlike pirates, the privateers raided not just for themselves, but on behalf of their governments, who not only permitted, but often funded, their missions.
Privateering originated in 1243, when King Henry III of England issued the first Letter of Reprisal. This letter was a license to attack enemy ships without fear of punishment, and was the precursor to the Letter of Marque, granted to privateers in later centuries. The ships granted these licenses were originally called 'private men-of-war,' and the name was later shortened to privateers. In return for its support, the government received a portion of the loot, and also added to its military without having to pay additional men. For European countries, embroiled in a seemingly endless series of wars, the additional manpower was necessary for survival. This was especially true for England, which couldn't afford to build a navy formidable enough to match its foe, the Spanish Armada. Spain dominated the seas during the early 1500s, and its conquests to the New World had made it wealthy and powerful. England depended on the privateers to help it claim some of these riches as its own.
The most famous of the English privateers--John Hawkins, Francis Drake and Walter Raleigh--were called the 'Sea Dogs.' The name was given to them by Queen Elizabeth I, who supported their sea missions, and who became wealthy from the proceeds of their raids. In 1581, Elizabeth knighted Drake, whom she called 'my pirate.'
Privateering, unlike piracy, was recognized as a profession. These privateers acted in service to their country, and many of them gained both wealth and social standing. Though considered more respectable than pirates, not all privateers embodied nobility and patriotism, and some crossed the fine line between privateering and piracy by attacking friendly ships. Though the privateers had permission from their governments to attack enemy vessels, the enemy viewed them not as military, but as pirates. If captured, they were punished the same as any other criminal.
The earliest privateers commanded crews of between 40 and 50 men; their ships ranged from 50 to 100 tons. Later, they converted merchant ships that were nearly three times that size. The English ships were fast, heavily armed, and easy to steer. They were also low, unlike the massive structures favored by the Spanish. English privateers trained their gun crews frequently, because they preferred gun battles to close combat. English privateers had to follow strict rules: only enemy cargo could be seized, and all loot must first be brought to the ship's home port, where Admiralty Officers inventoried and appraised every item.