A "Letter of Marque" is a government-issued document that authorizes a private individual or ship to engage in acts of piracy against enemy vessels. This legal permission allows the holder to capture enemy ships and their cargo, effectively turning them into privateers. The practice was common during times of war, as it provided a way for nations to bolster their naval power without maintaining a large fleet. Historically, letters of marque were used by various countries, including England, France, and Spain, especially during the Age of Sail. The captured ships would often be brought to port, where the privateer could sell the goods and share the profits with the government. This system blurred the lines between piracy and legitimate naval warfare.