 On 1 November 1918 , the transfer being still unknown , two men of the Regia Marina , Raffaele <unk> and Raffaele Rossetti , rode a primitive manned torpedo ( nicknamed the <unk> or " leech " ) into the Austro @-@ Hungarian naval base at Pola . Using limpet mines , they then sank Viribus Unitis , as well as the freighter Wien . 
