About the time of the Mexican–American War in 1846, the United States Navy had grown strong and numerous enough to eliminate the pirate threat in the West Indies. By the 1830s, ships had begun to convert to steam propulsion, so the Age of Sail and the classical idea of pirates in the Caribbean ended. Privateering, similar to piracy, continued as an asset in war for a few more decades and proved to be of some importance during the naval campaigns of the American Civil War.