When the American Civil War broke out in 1861, Edwin Stevens claimed that a completed Stevens Battery would have a decisive impact against Confederate forces. Hoping to prove his point, he purchased an iron-hulled steamer and modified her greatly into a warship that would demonstrate to the U.S. Navy some of the principles he had in mind for the Stevens Battery, including high maneuverability, a respectable top speed, a semisubmersible capability, and a large gun on the main deck capable of a high rate of fire and loaded from below the deck by gun crews protected by armor.