Purely as a film I give ENIGMA 6 out of 10; as an historical document zero. Generally I do not necessarily expect a film with an historical content to be a piece of cinematic non-fiction but merely a source of entertainment, so I score it on this basis. If the distributors claim it as a true historical record then that is another matter. Enigma has a fairly good plot but suffers from poor direction and frequently indistinct dialogue. It centres around a young man and a young girl working at the Government's code deciphering establishment at Bletchley Park and their involvement in the breaking of the German U-boat cipher SHARK (or TRITON to give it its original German name). As the mechanics of the breaking of SHARK has little story value a sub-plot involving a femme-fatale as German spy is introduced.
During 1941 our Atlantic convoy losses were becoming unsustainable so the ability to read SHARK was imperative. The film has a section in which the code breakers are shown helping a naval lieutenant to pinpoint the position of U-boats in the Atlantic based on wireless direction finding information. This was not the work of Bletchley Park so is historically wrong. In fact,convoys and U boats were tracked by the Admiralty in London.
The film also purports that breaking SHARK was the sole factor in helping to bring down convoy losses. The truth is somewhat more ironic. Whilst we could not read TRITON/SHARK the Germans could read the Royal Navy Cipher No. 3! However it took us a year to find out. It was this cipher which was used to transmit the rendez-vous points for departing convoys to RN escort vessels in the North Atlantic. The Germans picked this up at their listening stations and promptly re-transmitted it to their U-boat wolf packs who were then able to proceed to the rendez-vous ready to pick off their prey. This information was sent in SHARK so once it was broken we knew that RN Cipher No.3 was being compromised and had to be changed. As a result convoy losses decreased.
The reason for the weakness in Cipher No.3 was that when WWII started the Royal Navy was essentially still using code book methods from the Great War and were very slow to adopt mechanical encipherment, similar to Enigma. On the other hand the RAF introduced it in the 1930s for use on the Defence Teleprinter Network run by the GPO. For this the Type-X machine was developed and was featured in the film for reading German enigma code. The German Enigma machine itself features prominently in the opening sequences of the film with several close-ups and supporting dialogue explaining how it worked.
Did the Germans know that we could read their enigma messages? This is a moot point as officially they did not but both Rommel and Doenitz, the U-boat commander, were highly suspicious; Rommel because convoys from Italy to North Africa were frequently sunk and Doenitz because U-boat code changes only gave him a short term advantage against convoys. In both cases the leakage was blamed on spies, although it has been suggested that Doenitz's staff were very possibly convinced but dare not tell Hitler that Enigma was compromised, so they just contented themselves with improving the system. Unlike the British centralised Intelligence centre at Bletchley Park the Germans had separate intelligence staffs for each of the three services with the inevitable rivalry between them. This weakened their counter intelligence operations which, coupled with the extreme secrecy surrounding Ultra, meant that our success against Enigma went undetected.
The film is well worth seeing for its entertainment value and just a wee peek at the work of Bletchley Park but for anyone interested in learning the truth about this fascinating story I suggest that they read the official history entitled "British Intelligence in WWII" by Professor Sir F. H. (Harry) Hinsley (himself an alumnus of BP), or just Google "Bletchley Park".
