 The participating commandos were captured after setting limpet mines which sank two Allied ships and damaged two more.On 4 December 1942, the Italian submarine "Ambra" of the Italian Royal Navy ("Regia Marina") left the naval base of La Spezia, carrying three manned torpedoes and 10 commando frogmen.Air recoinnassance had discovered that the port of Algiers was crowded with Allied cargo ships, thus the Italian high command had decided to launch a combined operation involving both human torpedoes and combat swimmers carrying limpet mines.