Early in the American Civil War, St. Louis shipyard owner James Eads proposed converting a “snag boat” – a catamaran stern wheel boat designed to lift snags out of the river – to an armored vessel. Secretary of the Navy Gideon Welles liked the proposal, and the US began building a series of ironclad river gunboats. These had a less glamorous career than the more famous ocean going ironclads, like the Monitor; the only time they faced a Confederate vessel, the Arkansas, they were humiliated, but they were still instrumental in winning the war for the Union by bombarding forts and interdicting river traffic.
This is a typical Osprey book; fairly pricy, lots of illustrations (including a color plate section), good for the military modeler. ( )