one-man submarine, the first to be put to military use, built and designed by the American inventor David Bushnell (Bushnell, David) (q.v.) in 1775 for use against British warships. The pear-shaped vessel, made of oak reinforced with iron bands, measured about 2.3 m (7.5 feet) long by 1.8 m (6 feet) wide. It was equipped with a mine that was to be attached to the hull of an enemy ship. In 1776, in New York harbour, the Turtle tried to sink the British warship HMS Eagle but failed; none of its succeeding missions was successful.