The Mark 20 torpedo was a US torpedo designed in 1943 but never used in service. Design was by Naval Torpedo Station Newport, the Electric Storage Battery Company and General Electric. This project was a continuation of the development of a submarine-launched, anti-surface ship torpedo originally designated Mark 2 in 1941 which was the second attempt to develop a torpedo of this type. The earlier effort, designated Mark 1, in post-World War I years (1919-1931), was terminated after the torpedo produced proved unsatisfactory in speed and range.