Site navigation

Rare Enigma M4 Machine Sells for Bumper Price at Auction

Ross Kelly


Enigma M4

Allied codebreakers struggled to crack the M4 Enigma for 10 months. 

An iconic artefact from the Second World War has sold at auction for nearly half a million dollars. The Enigma M4 machine was sold for $440,000 (£347,250) to an anonymous buyer last week, with Christie’s handling the sale.

According to the description provided by Christie’s, the device is regarded as “one of the rarest and hardest Enigmas to decrypt” due to its use of four rotors instead of three.

Additionally, the operator’s ability to choose from a pool of eight interchangeable rotors gave the M4 Enigma a far higher level of encryption.

Introduced in 1942, the M4 successfully repulsed Allied codebreakers for 10 months; a feat that was out of the ordinary given extensive Allied efforts to crack German communications.

Under the leadership of Alan Turing and Joe Desch, efforts to break the M4 led to the development of the first programmable computer and helped turn the tide in the Battle of the Atlantic.

German u-boats prowled the crucial Atlantic sea routes upon which men and materials flowed from the United States to Britain. Initially, u-boat ‘wolf packs’ inflicted a heavy toll on Allied merchant shipping.

However, once the German Navy’s Morse code communications were deciphered, Allied naval assets were able to track and counter-act German u-boat attacks.

Repeated Allied successes against u-boats raised the concern of Admiral Karl Donitz, head of Nazi Germany’s Navy, the Kriegsmarine.

Although German engineers did not believe the Allies were capable of cracking encrypted communications, Donitz still ordered the development of the special 4-rotor Enigma.

“Despite the fact that the Allies were by then regularly reading messages coded by earlier versions of the Enigma, German investigators determined that it was impossible for the Allies to read Enigma messages,” the Christie’s description reads.

“It was thought that the Allies had used espionage, or radar, or simply had chanced upon the submarines,” Christie’s added.

After the war, Donitz still professed his faith in the M4 Enigma during the Nuremberg Trials. The Admiral, who briefly succeeded Hitler as German head of state in 1945, insisted the Allies could not have deciphered Enigma messages and believed that advances in radar had turned the tide.


It is believed that fewer than 100 of the devices survived the war. This is largely due to the fact they were produced in far smaller numbers than 3-rotor machines.

Additionally, the majority of these devices were deployed on u-boats, which often meant they were lost in combat or after a vessel was scuttled by its crew.

Similarly, toward the end of the Second World War, German troops were ordered to destroy their machines rather than cede them to enemy forces. On the Allied side, Churchill ordered the destruction of all remaining Enigma devices after the war in order to ensure the secrecy of Bletchley Park’s successes.

This isn’t the first cipher machine to have recently fetched a high price at auction. In December 2019, an SG-41 cipher machine, known as a “Hitler-Mill”, was purchased by an Irish collector for £87,000.

The SG-41 was far more sophisticated than the Enigma device, using six encoding wheels instead of the Enigma’s three, and was developed by Nazi engineers after Bletchley Park codebreakers cracked the Enigma code in 1941.

A fully-functioning M4 Enigma machine also sold at auction for $435,000 in 2017, with Sotheby’s handling the sale.

Ross Kelly

Staff Writer

Latest News

Cloud Data Protection Editor's Picks Featured
Editor's Picks Gaming
%d bloggers like this: