Based upon the experiences and successes of the Italian Regia Marina in the First World War. In 1935 Teseo Tesei and Elios Toschi developed and perfected the Siluro a Lenta Corsa (S.L.C.), which was more informally known as "Maiale” (Pig). This was a torpedo modified to allow it to be guided underwater by two operators equipped with respirators. It was intended to carry a high explosive warhead under the keel of enemy ships. The modified torpedoes had limited speed, were fitted with a guidance system and held batteries that powered the electric motor which guaranteed a range of 12-15 miles. The most notable action of these Italian Navy raiders took place on 19th December 1941. Transported by the submarine "Scire" to the strongly defended Alexandria harbour, the S.L.C.’s were able to attack and disable for several months, Royal Navy battleships H.M.S: Valiant and the H.M.S. Queen Elizabeth.
