During the
Middle Ages, armed private vessels enjoying their sovereign's tacit consent, if not always an explicit formal commission, regularly raided shipping of other states, as in the case of the English
Sir Francis Drake's attacks on Spanish shipping.
Queen Elizabeth I (despite protestations of innocence) took a share of the prizes. Dutch jurist
Hugo Grotius's 1604 seminal work on international law,
De Iure Praedae (
Of The Law of Prize and Booty), was an advocate's brief defending Dutch raids on Spanish and Portuguese shipping.
King Henry III of England first issued what later became known as privateering commissions in 1243. These early licences were granted to specific individuals to seize the King's enemies at sea in return for splitting the proceeds between the privateers and
the Crown. The letter of marque and reprisal was documented in 1295, 50 years after wartime privateer licenses were first issued. According to Grotius, letters of marque and reprisal were akin to a "private war", a concept alien to modern sensibilities but related to an age when the ocean was lawless and all merchant vessels sailed armed for self-defense. A reprisal involved seeking the sovereign's permission to exact private retribution against some foreign prince or subject. The earliest instance of a licensed reprisal recorded in England was in the year 1295 under the reign of
King Edward I. The notion of reprisal, and behind it that
just war involved avenging a wrong, was associated with the letter of marque until 1620 in England. To apply for such a letter, a shipowner had to submit to the Admiralty Court an estimate of actual losses incurred. Licensing privateers during wartime became widespread in Europe by the 16th century, when most countries began to enact laws regulating the granting of letters of marque and reprisal. Such business could be very profitable; during the eight years of the
American Revolutionary War, ships from the tiny island of
Guernsey carrying letter of marque captured French and American vessels to the value of
£900,000 (). Privateers from Guernsey continued to operate during the
Napoleonic Wars. Although privateering commissions and letters of marque were originally distinct legal concepts, such distinctions became purely technical by the 18th century.
Article I of the
United States Constitution, for instance, states that "The
Congress shall have Power To ... grant Letters of marque and reprisal ...", without separately addressing privateer commissions. During the American War of Independence, the Napoleonic Wars, and the
War of 1812, it was common to distinguish verbally between privateers (also known as private ships of war) on the one hand, and armed merchantmen, which were referred to as "letters of marque", on the other, though both received the same commission. The
Sir John Sherbrooke (Halifax) was a privateer; the
Sir John Sherbrooke (Saint John) was an armed merchantman. The
East India Company arranged for letters of marque for its
East Indiamen ships, such as the
Lord Nelson. They did not need permission to carry cannons to fend off warships, privateers, and pirates on their voyages to India and China but, the letters of marque provided that, should they have the opportunity to take a prize, they could do so without being guilty of piracy. Similarly, the
Earl of Mornington, an East India Company
packet ship of only six guns, also carried a letter of marque. Letters of marque and privateers are largely credited for the
age of Elizabethan exploration, because privateers were used to explore the seas. Under the Crown,
Sir Francis Drake,
Sir Walter Raleigh, and
Sir Martin Frobisher sailed the seas as privateers; their expedition reports helped shape the age of Elizabethan exploration. In July 1793, the East Indiamen ,
Triton, and
Warley participated in the capture of
Pondichéry by maintaining a
blockade of the port. Afterwards, while sailing to China, the same three East Indiamen participated in an action in the
Straits of Malacca. They came upon a French
frigate, with some six or seven British prizes, with a crew replenishing her water casks ashore. The three British vessels immediately gave chase. The frigate fled towards the
Sunda Strait. The Indiamen were able to catch up with a number of the prizes, and, after a few cannon shots, were able to retake them. Had they not carried letters of marque, such behaviour might well have qualified as piracy. Similarly, on 10 November 1800, the East Indiaman
Phoenix captured the French privateer
General Malartic, under
Jean-Marie Dutertre, an action made legal by a letter of marque. Additionally, vessels with a letter of marque were exempt from having to sail in
convoy, and nominally their crew members were exempt, during a voyage, from
impressment. During the Napoleonic Wars, the
Dart and
Kitty, British privateers, spent some months off the coast of
Sierra Leone hunting slave-trading vessels. ==Applying for, and legal effect of, a letter of marque==