ENIGMA M4 | A FULLY OPERATIONAL FOUR-ROTOR ("M4") KRIEGSMARINE ENIGMA CIPHER MACHINE. BERLIN-WILMERSDORF, GERMANY, HEIMSOETH UND RINKE, 1942, SEIZED FROM THE BAUAUFSICHT DER KRIEGSMARINE IN TRONDHEIM, NORWAY, AFTER THE CAPITULATION OF NAZI FORCES...

ENIGMA M4
A fully operational four-rotor ("M4") Kriegsmarine Enigma Cipher Machine. Berlin-Wilmersdorf, Germany, Heimsoeth und Rinke, 1942, seized from the Bauaufsicht der Kriegsmarine in Trondheim, Norway, after the capitulation of Nazi forces there in 1945

Four-rotor ("M4") Kriegsmarine Enigma cipher machine, serial number 5124/JLA/42, complete with Beta rotor (M3174), 3 aluminum rotors (IV, VI, & VII) with serial numbers (VI: M8423, IV, VIII: M10138), and C reflector (M3174), each rotor with 26 positions labeled with letters. Housed in the original oak case (13¾ x 11¼ x 6¼ in.), with leather handle, case with hinged front panel stamped "Klappe Schleissen" opening to reveal ebonite Steckerbrett [plug-board], outside of case and inside of lid with matching metal plates reading "M 5124." Control panel with standard raised "QWERTZ" keyboard of 26 Bakelite keys in white on black backgrounds, lockable rotor cover, battery compartment and 4V power socket and key, removable light panel with letters A-Z lifting to reveal 26 light bulbs, Steckerbrett with 12 original patch cables (10 plugged into the Steckerbrett and 2 spares stored in lid of case), lid with 10 spare bulbs, green contrast filter, spare patch cables, original paper instruction label, (stamped serial 5124), and stamped "Admiral Norwegen | Kommando der Marine Station Ostsee" above the instruction label.

[WITH]: additional aluminum rotor (II: M5569) in secondary oak storage case (5¼ x 10¼ x 5 in.), outside of case and edge with matching metal plates reading "M8423," inside of lid with the effaced stamp of "Kommando de Marine Station Ostee," and the additional stamp: "Marineoberkommando | In Norwegen | Druckschriftenverwaltung," [AND] Original German telegraph key (D.R.P Junker), and five facsimile user manuals.

A VERY FINE AND FULLY OPERATIONAL EXAMPLE OF THE FAMOUS GERMAN FOUR-ROTOR ("M4") KRIEGSMARINE ENIGMA CIPHER MACHINE, WITH PROVENANCE TRACING BACK TO OCCUPIED NORWAY. THE RAREST AND MOST DESIRABLE OF ALL ENIGMAS, THE M4 WAS ONE OF THE HARDEST TO DECRYPT. VERY FEW M4 MACHINES SURVIVED THE WAR, AND TO FIND ONE THAT IS COMPLETE, WITH TRACEABLE PROVENANCE, STILL IN SUCH PRISTINE CONDITION, AND FULLY OPERATIONAL IS RARE INDEED.

The M4 Enigma machine was an electromechanical cipher machine specifically developed for use by the U-boat division of the German Navy (Kriegsmarine) for communication with the naval bases, where it played a pivotal role in the Battle of the Atlantic. Admiral Karl Dönitz, the commander of the U-boat fleet seriously doubted the security of the Enigma after several unexplained losses, and had the secret M4 model developed specifically for his fleet. The M4 was ready around May of 1941, and by February of 1942 all M4 machines had been distributed with the new operating procedures placed into effect.

The present example was one of 15 Enigma machines in daily use at a communications bunker and headquarters for the Admiral North Kuste at the Kriegsmarine base in Trondheim, Norway. Following the occupation in 1940, this became the largest German naval base in northern Europe, and the base housed the 13th U-Boat Flotilla, and some 55 U-boats. Norway was an important strategic asset for Germany, as it facilitated access to iron ore from Sweden, and to the North Atlantic and Arctic Oceans. Critical information passed through the Trondheim communications bunker, such as weather observations sent from U-boats in the north Atlantic, among other things. The assorted serial numbers found on the aluminum rotors in the present machine are a good indication of consistent wartime usage, as German operators frequently swapped out rotors from other machines.

While the codebreakers at Bletchley had been reading messages encrypted by the 3-Rotor machines for some time, the introduction of the M4 caught them completely off-guard, shutting them completely out, and it took them a full 9 months to catch up and solve the new code. Few Enigma machines survived the War intact: the Germans destroyed them as they retreated, and for decades after the war governments around the world kept close control over Enigma technology (indeed two of Turing's wartime papers on cryptography remained classified until 2012). So secure was the system believed to be that some governments, unaware of the work of Bletchley Park, continued to use Enigmas after 1945.

The M4 was a variation of the 3-rotor Enigma I machine used by the Wehrmacht (German Army & Airforce). It accepted 3 standard rotors and a narrow fourth rotor in combination with a narrow reflector. The two narrow components allowed all four rotors to fit into a modified three-rotor Enigma chassis. It was issued with eight standard rotors, the first five having wiring identical to the rotors issued with the three-rotor Enigma-I. Two narrow fourth rotors, Beta and Gamma, were also issued with each machine. With the fourth narrow rotor in the "A" position, the M4 became functionally identical to and could...