The listening service, or "Ahrendstationen",
was formed towards the end of 1915, but it was only in January 1917 that these
became independent units. In February 1917 there were 22 Arendt-Abteilungen .
In March 1918 they were restructured into 292 Arendt-Stationen. Of these, one
was attached to each division leaving a number free as a reserve. The staffs of
the now defunct Abteilungen were reassigned to the Akonach and Grukonach to
process the information from the messages picked up by the stations.
Until 1916 there was a carefree exchange of
conversation on the field telephone lines. There were few apparent dangers and
no conceivable negative effects. At some point in 1916 the Germans began to
suspect that their communications were being overheard. This suspicion was
confirmed when special communications equipment was discovered in a captured
enemy trench. The fact that the enemy could branch themselves directly onto a
telephone line was not the issue as the telephone lines ran behind the German
positions, rather, the enemy was using the electrical current in the earth to
Above: A Telephone post in a front line bunker
A field telephone operated in an electrical circuit,
the message only being transmitted when the current went from the sender to the
receiver and back again. This required 2 cables between telephones. An
alternate system had been developed to save the confusion that would be caused
by having double the amount of cables being strung between positions. The
second wire, instead of being connected between the two telephones was connected
between the telephone and a steel peg or bayonet, which in turn was stuck into
the damp earth, in this way the current would be carried by the earth from one
telephone to the other.
The catch was, the current did not travel directly
from one bayonet to the other, but radiated in all directions. If one was to
put another cable into the ground, a "searcher cable", it was
possible to pick up these currents, usually to weak to be of any use. With a
system of valves and special light bulbs the enemy had succeeded in increasing
this current to a point where he could listen in on the telephone conversation
of the German signalers. The Germans immediately tried to implement counter
measures, including running an "earth wire" with a length of 4-500 meters
behind their line. This did not seem to have any effect, so they were forced to
do away with the earthing system and run double lines between telephones. It
was soon discovered that only telephone lines in perfect condition were secure.
Any slight damage to the isolating cover would mean the wire would give off
current and this in turn would radiate to enemy listening posts.
The German signalers did not take long in creating
their own listening stations, named "Ahrendtstationen" after their
founder. These rapidly surpassed the technology and efficiency of the enemy
stations. Signalers would often sneak across no mans land and earth their
searcher cables directly in front of the enemy positions, or alternately attach
them to the enemy barbed wire, which acted as a superb conductor. The results
were extremely satisfying to the German high command.
Above: The Iron Cross award document to a member of the Arendt Abteilung of the 3rd Army Headquarters.
It did not take long for the enemy to realize that the
Germans now also had listening posts. The counter measures were limited, as on
the German side, to implementing a double wire system. This could not prevent
the enemy listening in, but did limit the amount of traffic he could listen to.
Both sides imposed strict control on telephone conversations, including the
content and frequency. Lines not of tactical necessity were removed and front
line units were limited to only the bare minimum of calls, once again limited
to those of tactical necessity.
The Arendt-Stationen, in addition to their task of
listening in on enemy conversations also listened for enemy tunnelers and
miners as well as being responsible for listening in on German conversations.
All conversations, both enemy and friendly, were recorded and sent to the rear
to be controlled. This allowed the staff to sanction those who had breached the
rules related to telephone security and access what information may have been
intercepted by enemy listeners.
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