cause the boat to resurface. In 1749, the Gentlemen's Magazine reported that a similar design had initially been proposed by Giovanni Borelli in 1680. Further design improvement stagnated for over a century, until application of new technologies for propulsion and stability. The first military submersible was (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. 19th century In 1800, France built , a human-powered submarine designed by American Robert Fulton. They gave up on the experiment in 1804, as did the British, when they reconsidered Fulton's submarine design. In 1850, Wilhelm Bauer's Brandtaucher was built in Germany. It remains the oldest known surviving Submarine in the world. In 1864, late in the American Civil War, the Confederate navy's became the first military submarine to sink an enemy vessel, the Union sloop-of-war , using a gun-powder-filled keg on a spar as a torpedo charge. The Hunley also sank, as the explosion's shock waves killed its crew instantly, preventing them from pumping the bilge or propelling the submarine. In 1866, was the first submarine to successfully dive, cruise underwater, and resurface under the crew's control. The design by German American Julius H. Kroehl (in German, Kröhl) incorporated elements that are still used in modern submarines. In 1866, was built at the Chilean government's request by Karl Flach, a German engineer and immigrant. It was the fifth submarine built in the world and, along with a second submarine, was intended to defend the port of Valparaiso against attack by the Spanish Navy during the Chincha Islands War. Mechanically powered submarines Submarines could not be put into widespread or routine service use by navies until suitable engines were developed. The era from 1863 to 1904 marked a pivotal time in submarine development, and several important technologies appeared. A number of nations built and used submarines. Diesel electric propulsion became the dominant power system and equipment such as the periscope became standardized. Countries conducted many experiments on effective tactics and weapons for submarines, which led to their large impact in World War I. 1863–1904 The first submarine not relying on human power for propulsion was the French (Diver), launched in 1863, which used compressed air at . Narcís Monturiol designed the first air-independent and combustion-powered submarine, ,