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The Service Enigma
In 1926, the German Army - then called the Reichswehr - adopted the Enigma machine.
In early 1927, the first machine with an single-ended Steckerbrett
(plug board) was developed.
Later that year, the final version was released,
with an improved double-ended Steckerbrett.
It was based on the chassis of the Enigma D
and was given the internal designator Ch. 11a.
The first batch of machines (approx. 600 units) were delivered on 10 December 1927.
The Rechswehr (the predecessor of the Wehrmacht) called this machine
the Enigma I.
It would be the standard on which all further Enigma machines,
used by the German Army, were based.
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This version of the Glühlampenmaschine (lamp machine) has three
moving code wheels, a fixed reflector (UKW) and a Steckerbrett
(plug board).
The Steckerbrett was used exclusively for the German Army.
It was supplied with 5 different coding wheels, numbered I to V.
Each wheel had 26 positions and had numbers (01-26) on the circumfere.
The wiring of each wheel is given below.
About 20,000 machines of this type were manufactured by various
manufacturers, but only a hand full have survived.
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The Enigma I was used by both the Wehrmacht (Army) and the
Luftwaffe (Airforce).
It was later adopted by the Kriegsmarine (German Navy) where it was
commonly known as the M3 (preceeded by the M1 and the M2).
The only obvious differency between the Army version and the
Navy version is that the wheels of the latter have letters (A-Z) around their
perimiters.
The machine is known by different names:
- Wehrmacht Enigma
- Heeres Enigma
- Army Enigma
- Service Enigma
- Army/GAF Enigma
- 3-wheel Enigma
- 3-wheeler
but the official name for it is Enigma I (Roman number 1)
or Ch.11a.
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The Enigma I was supplied with 5 coding wheels, but only 3 of them
were in the machine at any time. Each day, the operator would place
3 wheels in the machine in a particular order, as instructed by the
codebook.
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The remaining two (unused) wheels were stored in a small wooden box.
The image on the right shows an example of such a storage box with
two wheels.
In the picture, wheels I and V are currently stored inside the box,
whilst wheels II, III and IV are fitted in the machine.
Other types of boxes are known to exist, but this is the most
common model.
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During WWII, the Germans made several attempts to
make the Enigma more secure.
In July 1944, the German Luftwaffe came up
with a smart device called Enigma Uhr, which was
introduced without any prior warning whatsoever.
It was attached to the side of an Enigma I and
connected directly to the Steckerbrett.
 More information
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Below is the wiring for each wheel, the ETW and all three known
UKWs. UKW-A was used before WWII [1]. UKW-B was the standard reflector
during the war and UKW-C was only temporarily used during the war.
The wiring of all 5 wheels is identical to the wiring of the
first 5 wheels of the Enigma M3 (used by
the Kriegsmarine) and the U-Boot Enigma M4.
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| Wheel |
ABCDEFGHIJKLMNOPQRSTUVWXYZ |
Notch |
Turnover |
# |
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| ETW |
ABCDEFGHIJKLMNOPQRSTUVWXYZ |
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| I |
EKMFLGDQVZNTOWYHXUSPAIBRCJ |
Y |
Q |
1 |
| II |
AJDKSIRUXBLHWTMCQGZNPYFVOE |
M |
E |
1 |
| III |
BDFHJLCPRTXVZNYEIWGAKMUSQO |
D |
V |
1 |
| IV |
ESOVPZJAYQUIRHXLNFTGKDCMWB |
R |
J |
1 |
| V |
VZBRGITYUPSDNHLXAWMJQOFECK |
H |
Z |
1 |
| UKW-A1 |
EJMZALYXVBWFCRQUONTSPIKHGD |
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| UKW-B |
YRUHQSLDPXNGOKMIEBFZCWVJAT |
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| UKW-C |
FVPJIAOYEDRZXWGCTKUQSBNMHL |
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