Gunboat
Gunboats experienced a revival during the American Civil War (1861–1865). Union and Confederate forces quickly converted existing passenger-carrying boats into armed sidewheel steamers. Later, some purpose-built boats, such as , joined the fray. They frequently mounted 12 or more guns, sometimes of rather large caliber, and usually carried some armor. At the same time, Britain's gunboats from the Crimean War period were starting to wear out, so a new series of classes was ordered. Construction shifted from a purely wooden hull to an iron–teak composite.