Privateering is the hiring of privately owned ships and their crews to fight during battle. The practice, dating back to the 1400s, continued well into the 1800s, eventually replaced by the development of strong navies. Privateers were, essentially, gunboats for hire. They played a crucial role in the American Revolutionary War (1775–83) after the Second Continental Congress authorized their use on March 18, 1776, enabling the colonists to capture about 600 British ships. The Americans would again employ privateers in the War of 1812 (1812–14).

But during times of peace, some privateers turned to pirating, which at least in part prompted European nations to sign the Treaty of Paris of 1856, which ended the Crimean War (1853–56) and outlawed privateering. Since the United States had relied on privateers in the past and had yet to develop its own navy, the Americans did not sign the treaty. While there was some privateering during the American Civil War (1861–65), the need for them soon subsided as navies developed—by enlistment and draft. Privateering has not been used in more than 100 years.