One of the rarest of all Enigma Machines, the M4 designed for use by the German Navy during World War II, leads Bonhams’ History of Science and Technology Sale in New York on 7 December.
The fully operational machine dating from 1943 is estimated at $280,000-$350,000.
The M4 Naval Enigma was ordered in 1941 when the head of the German Navy Admiral Karl Doenitz believed, correctly, that the security of the Naval M3 Engima had been compromised.
The M4 was reserved for deployment by U-boat forces on land and at sea to enable the Naval High Command to communicate securely with the U-Boat fleet. The machine in the sale is in fine condition and is, therefore, believed to have been used from a base on shore rather than from a U-Boat.
Bonhams science and technology specialist Tom Lamb said: ‘Only 120 M4 Enigma machines are believed to have survived. These are mainly in official hands making this a particularly rare opportunity for collectors to acquire one of the iconic machines of the Second World War. It is in perfect working order.’
The early Enigmas had three interchangeable rotors that scrambled plain-text messages to produce a cipher text message, which was then sent via Morse code to a receiver machine with the same settings.
The three rotor code was broken early on in the war by the code breakers at Bletchley Park but when the M4 came into use on 1 February 1942 it took over nine months for Bletchley to crack the new code. The breaking of the Enigma codes by the Allies is regarded as having shortened the war by at least two years.
The sale also includes a rare three-rotor German Enigma I Enciphering Machine, estimated at $150,000-$250,000. Also dating from 1943, this machine would have been used principally by the army.
It is not known exactly how many of these machines were made, but their survival rate is very low. There are around 40 examples in museums around the world.
The three-rotor Enigma was used by the German army up to end of the war, by the navy until 1942, and also by the Air Force until c.1944. At the end of the war, rather than have the machines fall into enemy hands, they were destroyed by the German forces upon retreat, many simply thrown into rivers and lakes.