'Enigma' parts discovered

Rotors from an Enigma machine Photo: Royal Navy

HMS Collingwood will be helping The National Museum of the Royal Navy at Portsmouth Historic Dockyard commemorate the 71st anniversary of the Royal Navy’s capture of an Enigma machine, as they reunite some very special items. May 9, 1941 was the date that the Royal Navy captured the first, fully functioning, Enigma machine complete with rotors and codebooks from the German U-boat 110.

CPO Craig “Blood" Read and PO Dan Powditch were cleaning out their store in MERCURY building in HMS Collingwood in Fareham when they found a box containing three rotors for an Enigma machine. Not being convinced they could be original, they put them back in a cupboard.

It was whilst getting some flags from the same store with CPO Jack Goozee, during Easter leave, that CPO Read got the box of rotors down and asked him what he thought they were. In his opinion they were probably Enigma machine rotors and after a few searches on the internet they discovered that the box was original and also the Senior Rates mess in the old HMS Mercury had donated a machine of the same number to the National Museum of the Royal Navy (NMRN). As both the museum’s machine and the rotors originated from HMS Mercury, the Royal Navy Signals School and Combined Signals School[i], it looks like the two have been separated for the last 29 years. They will now be reunited on the 9th May with an official handover at the NMRN by Commodore Mansergh to Professor Dominic Tweddle, Director-General of the Museum.

The Enigma Machine was donated to the NMRN in 1983 by HMS Mercury and is a type M4 machine. It was probably used by the Norwegian Harbour Police, but is missing the reflector. The first rotor, therefore, has been adapted to enable it to do the reflector’s job. This makes the machine an unusual specimen.

Richard Noyce, Curator of Artefacts at the NMRN explains: “The number M15653 on the machine matches the number on the box of rotors and the box is stamped with ‘Kommando der Marine Sation Der 021’ albeit smudged and difficult to read. With both items originating from HMS Mercury I think there can be no doubt the Enigma Machine and its spare rotors were originally together. We are thrilled to be reuniting them again as they are a key part of our history.”

The German military used the Enigma cipher machine during WW2 to keep their communications secret. The machine was available commercially during the 1920s, but the military potential of the device was quickly realised and the German army, navy and air force all used a more developed model of the machine to encipher their messages believing that it would make these communications impenetrable to the enemy.

The Enigma machine is an electro-mechanical device that relies on a series of rotating 'wheels' or ‘rotors’ to scramble plaintext messages into incoherent ciphertext. The machine's variable elements can be set in many billions of combinations, and each one will generate a completely different ciphertext message. If you know how the machine has been set up, you can type the ciphertext back in and it will unscramble the message. If you don't know the Enigma setting, the message remains indecipherable.

The German authorities believed in the absolute security of the Enigma. However, with the help of Polish mathematicians who had managed to acquire a machine prior to the outbreak of WW2, British code breakers stationed at Bletchley Park managed to exploit weaknesses in the machine and how it was used and were able to crack the Enigma code.

Breaking the Enigma ciphers gave the Allies a key advantage, which, according to historians, shortened the war by two years thus saving many lives.