Enigma: Rising Tide — On May 7, 1915, the RMS Lusitania was to be sank by a torpedo from the German submarine U-20, killing 1,198 of the 1,960 people on board (including many US citizens), forcing the US to intervene in World War I . The ship was never torpedoed and calmly arrived at the port, but incriminating evidence against the British government was found on board: the future British Prime Minister Winston Churchill demanded that the ship sink, and the more Americans killed, the better it would be for Great Britain.