The world’s oldest naval ENIGMA

The German ENIGMA cipher machine is undoubtedly one of the most iconic artefacts of the World War Two era. Mysterious, fast and allegedly unbreakable, the crypto machine was at the very epicenter of a secret ‘cyberwar’ between Hitler’s Third Reich and a team of hard-working codebreakers at the British Bletchley Park, spearheaded by the famous mathematician and computer theorist Alan

A piece of history 'awaiting surgery'. M522 at the X-ray table.

A piece of history ‘awaiting surgery’. M522 at the X-ray table.


We have a particularly interesting ENGIMA in our museum collections: M522, a specimen from the very first batch of naval cipher machines, produced for the German Kriegsmarine in 1934. In fact,

it is one of the oldest military versions of the machine, as the first German army type (ENIGMA 1) only saw the light of day in 1932. The earliest patent is from January 1918 and the first functioning apparatus had been completed already in 1923, but the primary generation of ENIGMA machines were commercial models, intended for usage by banks and other security-minded firms.

Therefore, M522 represents a technological turning point in the development and usage of the fabled electro-mechanical crypto apparatus. It belongs to the so-called M1 series, where “M” stands for marine or naval. 611 copies of the M1 model were produced for the Kriegsmarine and only three of these are known to still exist today. One of them is our M522, which has the lowest serial number in the surviving sample, making it the oldest existing naval ENIGMA in the world. Most remaining versions of the naval ENIGMA are primarily so-called M3’s and M4’s, which were introduced at later stages in history, the last in February 1942 for the U-boat section of the German navy.

So our ENIGMA is quite a gem for anyone interested in cryptology, history, signals intelligence or the origins of the electronic computer. However, it is also a rather worn out version, clearly marked by time and war – and large amounts of saltwater. It was fished up from the bottom of the sea by a Danish fisherman in the early 1990’s, somewhere in the waters around Flensborg Fjord.

The details and circumstances of the finding are still under investigation. The museum will send a research team to southern Denmark to look deeper into the matter and interview some of the

Inside the ENIGMA. An X-ray of the past.

Inside the ENIGMA. An X-ray of the past.

people involved. Results and reports of this research mission will be published continuously on this blog.

It should be mentioned, however, that the object history of M522 is peppered with uncertainties and obscure areas. The very serial number was actually unknown to us until last year, when we decided to have a closer look at our mysterious WW2-artefact, which has been in our possession since the beginning of the 2000’s.

We actually had it X-rayed at the conservation department of the National Museum of Denmark, and we have established a close, professional dialogue with a number of international ENIGMA experts, most notably Frode Weierud (Norway), Paul Reuvers (Holland) and the retired Danish intelligence officer Niels Faurholt. It was Reuvers – manager of the fascinating Cryptomuseum – who discovered the serial number, by enhancing the X-ray photographs of the machine’s dark and enigmatic interior.

Here is a short film clip from April 2016 where I present our precious M522 for the Danish Broadcasting Corporation (DR) – in Danish (with a good Swedish accent).

Cracking the code: M522, the elusive serial number.

Cracking the code: M522, the elusive serial number.


Andreas Marklund

Andreas Marklund er forskningschef på ENIGMA og ph.d. i historie fra European University Institute i Firenze. Andreas Marklund is Head of Research at ENIGMA and has a doctorate in history from the European University Institute in Florence.

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