Two market segments are covered in different product lines. The military use is identified by the letter M and the commercial with K.
The transmitters of secrets worry about the risk of the breaking of the code by the competitor or the enemy. Around 1939 the Enigma K are equipped with a fourth rotor with the same automatic motion as the first three.
One of them was sold for € 45K before fees by Breker on April 18, 2015. Another one is for sale at the same auction house in Cologne on November 7, lot 24 estimated € 20K here linked on LiveAuctioneers. These two machines are not in matching numbers.
The control of the Atlantic is a key for winning the war. What could not be avoided happened: in 1941, a U-Boot was captured with its Enigmas. The concerned Kriegsmarine ordered a higher complexity of the Enigma. The M4 built from 1942 have their three automatic rotors plus a fourth rotor set by hand across 26 positions.
All submarines of the German Navy are equipped with two M4 Enigmas each between 1942 and 1944. Most of the M4 were destroyed in the sinking of their submarine, or by the officers before the surrender, or by the Allied forces after the capture.
An M4 in matching numbers is estimated $ 300K for sale by Bonhams in New York on October 21, lot 285. It is shown in operation in the video shared by the auction house (see below).
Another M4 with mismatched numbers of the rotors is estimated £ 80K for sale by Bonhams in London on October 27, lot 52.
AUCTION RESULTS :
Bonhams New York : SOLD for $ 365K including premium
Bonhams London : unsold
Breker : SOLD for € 31K before fees