sentences:  He was a volunteer in the Spanish Civil War with the rank of captain.In 1929, Tesei had the idea of the manned torpedo, from the Italian device used to sink the Austrian Battleship "Viribus Unitis" during World War I, and invented for the Italian "Regia Marina" what was later called the "Maiale".The modern Italian commando frogmen group COMSUBIN (Comando Raggruppamento Subacquei ed Incursori Teseo Tesei) is named after him.