The U-21 was a German submarine during WW1 and was the first sub to sink a ship with a torpedo, an English cruiser. This shocked the world. She was considered obsolete at the time, went on to sink two English battleships and a French transport, survived numerous attacks and sank 40 more ships. Commander Hersing stayed with the ship during the entire war and finally surrendered the sub to the English. It sank under tow back to England. The commander went on to become a successful farmer.