<P> The first military submarine was the Turtle (1775), a hand - powered acorn - shaped device designed by the American David Bushnell to accommodate a single person . It was the first verified submarine capable of independent underwater operation and movement, and the first to use screws for propulsion . </P> <P> In 1800, France built a human - powered submarine designed by American Robert Fulton, the Nautilus . The French eventually gave up on the experiment in 1804, as did the British when they later considered Fulton's submarine design . </P> <P> In 1864, late in the American Civil War, the Confederate navy's H.L. Hunley became the first military submarine to sink an enemy vessel, the Union sloop - of - war USS Housatonic . In the aftermath of its successful attack against the ship, the Hunley also sank, possibly because it was too close to its own exploding torpedo . </P> <P> In 1866, the Sub Marine Explorer was the first submarine to successfully dive, cruise underwater, and resurface under the control of the crew . The design by German American Julius H. Kroehl (in German, Kröhl) incorporated elements that are still used in modern submarines . </P>

What was the purpose of the submarine in ww1