 On February 1, 1942, the "Kriegsmarine" switched the U-boats to a new Enigma network (TRITON) that used the new, four-rotor, Enigma machines.This new key could not be read by codebreakers; the Allies no longer knew where the U-boat patrol lines were.This made it far more difficult to evade contact, and the wolf packs ravaged many convoys.