Page 187 - The Secret War in the Italian front in WWI (1915-1918)

CHAPTER NINE

Moreover, the interceptions carried out in January 1916 by Maria Zell’s station operating in the
area controlled by the 2 Army on the Isonzo front deserve particular attention . In that case,
11
nd
methodical listening operations were possible because of the regularity of enemy flights, which
usually took place between 11 and 12 a.m., when visibility was optimal in winter. Italian radio
telegraphists could therefore get ready to tune their receivers on aircraft emission frequencies.
Operators found out that when aircrafts achieved the vertical axis on the target, they transmitted
the telegraph signal FFF (Feuer) while after fire they repeated several times a signal, indicating the
approximate estimate in metres of the distance between the hit area and the target. For example:
200 - N - 50 - W.
The Intelligence Office of the 2 Army also provided some suggestions concerning the measures
nd
required to “make aircraft artillery fire information inaccurate or ineffective”. This ahead-of-
time electronic countermeasure entailed setting up adequately powerful transmitters that could
be quickly tuned into the frequencies of enemy aircrafts, to interfere with their communications.
The Austrian ground station of Aidussina, pinpointed by direction finding equipment in Codroipo
as located a few kilometres from Gorizia, tried to perform a similar function against some Italian
stations, aiming to disturb their radio communications that, right after enemy aircraft sighting,
would spread the alert across the whole area. However - as Sacco noticed - efforts to interfere
were unsuccessful because “the tone of the spark-gap station of Aidussina was quite different from
the tone of the Italian stations and this allows our radio telegraphists to follow warnings (alerts to
other Italian stations, A/N) despite attempted disturbance by the enemy”. The same Sacco adds:
“the enemy seems to be quite naive in insisting on this useless effort to disturb our radiotelegraphic
stations” .
12
For the same reason, the proposal set out in the above-mentioned report of the 2 Army to adopt
nd
a method analogous to that of the Aidussina station, to interfere with the Austrian air-to-ground
communications, was not immediately approved by the Engineer Corps Headquarters waiting
to become more familiar with the Austrian-Hungarian equipment by, for instance, seizing other
specimens .
13

True and false cIPhers

A letter of 22 February 1916 from the Intelligence Office of the Supreme Command to the 3
rd
Army Headquarters proves the first results of Italian efforts to break Austrian ciphers. That
document mentions an elementary mono-alphabetic substitution cipher used by some Austrian
radiotelegraphic stations where each letter is coded by a random two-figure number (B=93; C=62;
D=33, etc.), specifying that: “the numbers changed every 15 days […]” . The Intelligence Branch
14
of the 3 Army was asked to verify the eventual correspondence of this cipher to that used in
rd
Austrian radiograms intercepted by its stations. Evidently, that cipher shows extreme weakness

11 Intelligence Office of the 2 Army, Dalla stazione radiotelegrafica di Maria Zell, Radiotelegrammi intercettati ed interessanti
nd
osservazioni, fatte in proposito dalla suddetta stazione (Radio telegrams intercepted from Maria Zell’s radiotelegraphic
station and relevant remarks concerning the above-mentioned station), Bulletin no. 260, 26 February 1916.
12 3 Regiment of the Engineer Corps, Radiotelegraphic Office of Codroipo, Relazioni aprile-maggio 1916 (Reports, April -
rd
May 1916), op. cit., note on p. 5. ISCAG, Coll. 220.
13 General Headquarters of the Engineer Corps, letter to the Technical Office, 28 February 1916, op. cit.
14 Intelligence Office of the Supreme Headquarters, Cifrario per le comunicazioni telegrafiche austriache, (Cipher for
Austrian telegraphic communications), form n 67, personal in confidence, to the Chief of the Intelligence Office, 3 Army,
rd
o
22 February 1916.

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