This M4 Enigma, serial number M4117, was one of the first 4-Rotor M4 Enigmas to be manufactured by the Germans for their Navy. The manufacturer, Heimsoeth and Rinke, was assigned the manufacturer code jla in September of 1941 and since the machine carries the 1941 date, it must have been made between September and December of 1941. It was manufactured just before the first use of the M4 Enigma by German Navy U-Boats on 1 February 1942.

From the original “merkblatt” document inside the cover of the Enigma it is clear that this German Naval four-rotor Enigma was issued to the 24th U-boat flotilla that had a base in Trondheim, Norway on 3 July 1942. The 24 U-boat Flotilla was established in November 1939 as a training Flotilla to provide final training to future U-boat commanders. The four week training provided by this Flotilla was the final training that Kreigsmarine officers would receive before being assigned to an active U-boat. 53 U-boats were assigned to the 24th Flotilla during its service from 1939 to March of 1945 when it was disbanded.

This M4 Enigma was probably used at a command and communications facility on shore because it does not have the characteristic corrosion that is evident on Navy Enigma machines that were used at sea.

This Enigma was captured by the Norwegian military at the end of the war and surprisingly, it is believed to have been put into service in the Norwegian Navy for their own security operations from 1948 to 1957 during which time the world did not know that the Allies had successfully deciphered M4 Enigma messages. It is completely original, in working condition, and has a security feature that is unique -- in the wooden top of the Enigma is a black metal light panel shield that fits over the lock and a protrusion on the left of the cover that looks like a second lock. These two protrusions position the shield so that the operator of the Enigma who is typing the coded message or a person who is standing right next to the operator are the only people who can read the illuminated letters that display the deciphered message on the light bulb panel. This device provided increased security and prevented any bystanders from reading the deciphered messages.

Another particularly unusual feature of this Enigma is the appearance of numbers on the top and bottom rows of keys. All of the Enigma-encoded messages sent during the war consisted of only letters. The full name of a number was spelled out in letters whenever a number was required. Therefore, the purpose of placing numbers on the keyboard keys is unclear. They are not seen in later Marine Enigmas.

Another interesting feature is the M113 inscription that is cast directly into the top of the cast-metal base inside the Enigma and out of sight just behind the plugboard. It is not known what this signifies. This feature has never been seen in any other M4 Enigma.

The M4 Enigma is a variation of the three-rotor Enigma model “I” that was used by all branches of the Germany military from 1926 through 1945. The M4 accepted three standard rotors as well as a special fourth rotor in combination with a narrow reflector. The M4 was issued with eight rotors. Five of the eight rotors were identical in internal wiring with the five rotors issued with the three-rotor Enigma. With the forth special rotor in the “A” position, the M4 could communicate with the three-rotor Enigmas in use by other branches of the military.

Early in World War II, Karl Donitz, head of Germany’s U-boat fleet, had concerns over repeated Allied successes against his submarines. Despite the fact that the Allies were by then regularly reading Enigma coded messages, the German investigations into communications security determined that it was impossible for the Allies to read Enigma messages. It was thought that the Allies had either used espionage or radar or had accidentally encountered the submarines. Despite the outcomes of these investigations, Donitz ordered the development of a special four-rotor Enigma called the “M4” for use by the German Navy's U-boat fleet. The use of four rotors in the machine along with stricter operating procedures, and the ability to select among eight rotors, gave the German Navy M4 Enigma a higher level of encryption security and successfully defeated the Allies’ heretofore successful decryption of German Enigma coded signals for a period of ten months.

So confident was Karl Donitz in his communications security with the M4 Enigma that, after the war at the Nuremburg trials, he proclaimed that it was direction finding and advanced radar alone that had wreaked such destruction upon his fleet. It was impossible, he maintained, that the Allies had deciphered his Enigma messages.

However, brilliant mathematicians and engineers under the leadership of Alan Turing at Bletchley Park in England and Joe Desch in Dayton, Ohio in the United States, using information and ideas from Polish mathematicians had created what many call the world’s first programmable computers in efforts to successfully defeat the M4 Enigma code. By mid-1943, the majority of M4 Enigma messages were being read by the Allies. It was not until the 1970s that knowledge of the Allied successes against the Enigma was made public.

Very few M4 Enigmas survived the war. The reasons for this are that M4 Enigma machines were produced in much smaller quantities than the three-rotor machines. In addition, multiple M4 Enigmas were deployed with each U-boat and the majority of these were lost when the boats were sunk in combat or scuttled by their crews at the end of the war.

At the end of the war the Germans were ordered to destroy all of their Enigmas and after the war ended Churchill ordered all remaining Enigmas destroyed. These factors explain why Enigmas are so rare and of such interest to collectors and historians.

The significant role that the M4 Enigma and the secret Allied efforts to defeat its codes played in the vital Battle of the Atlantic has become increasingly well known as historians have revisited the history of WWII with recently declassified information that is still being evaluated to this day. These factors make the German Navy M4 Enigma the ultimate historical collectible and this particular M4 is unique amongst them.