When Is Piracy Legal? When Your Government Signs the Paper

A letter of marque was a document issued by a sovereign authorising a named private vessel to attack and seize the merchant shipping of a named enemy in time of war. The holder armed and crewed the ship at their own expense, received no pay, and was compensated entirely from the value of what they captured. Seized vessels had to be brought into port and condemned by a prize court, which examined whether the capture was lawful before ownership passed, and the proceeds were then divided among the owner, the captain and the crew by an agreed formula. Attacking neutral shipping or continuing after a war ended was piracy.

The attractions to a government were considerable:

• •Warships cost nothing, since private owners funded everything
• •A fleet could be expanded enormously within weeks of a war starting
• •Enemy trade could be attacked without diverting the regular navy
• •Ports gained employment building, fitting and crewing the vessels
• •The state took a share of the proceeds without risking capital
• •Crews served willingly, since the rewards could be very large

The system was open to abuse in ways that were obvious at the time and never solved. Distinguishing a licensed vessel from a pirate depended on a piece of paper that could be forged, bought from an obscure authority, or simply ignored once at sea. Holders attacked neutral shipping and claimed the victims were carrying enemy goods, which produced endless diplomatic complaint and litigation. Crews who had grown accustomed to the work continued after peace was declared, and a number of famous pirates began as licensed operators. Prize courts were slow and corruptible. And victims of a legal capture were ruined exactly as if they had been robbed, which made the distinction hard to explain to them.

The distribution of proceeds was set out in advance and is the part that explains why crews volunteered. A captured vessel and its cargo were valued after condemnation, and the total was divided by a fixed scheme, typically giving the owners who financed the voyage roughly half, the captain and officers a substantial share of the rest, and the ordinary crew a small but real portion each. A single rich capture could pay a seaman several years of wages, which no other maritime employment offered. The prospect distorted behaviour accordingly, with crews reluctant to engage a warship that carried no cargo worth taking and eager to pursue anything that did.

The practice was abolished by international agreement in the Declaration of Paris in 1856, signed by the major European powers at the end of the Crimean War, which declared it abolished among the signatories. The reasons were practical rather than moral. Steam and iron had made effective warships expensive and specialised, so converted merchant vessels were no longer militarily useful. Marine insurance and international trade had grown to the point where disruption hurt neutral and belligerent economies alike. The United States declined to sign, objecting that a nation with a small navy needed the option, and eventually stopped using it anyway. Commerce raiding continued under naval command and later by submarine.

A letter of marque authorised a private armed ship to seize enemy merchant vessels, with the owner funding everything and being paid entirely from condemned prizes. Governments gained a fleet at no cost within weeks of a war beginning. The paper could be forged or ignored, holders attacked neutrals and continued after peace, and several famous pirates began as licensed operators. An 1856 agreement abolished it among the major powers.