British Signal Security in North Africa, WWII Tactical and Technical Trends, No. 19: February 25, 1943 (Lone Sentry)

Radio, when properly used, furnishes a valuable means of signal communication. It is used for both tactical and administrative messages by all units of a modern army. It is an essential means for highly mobile elements such as aircraft and armored units, and is especially useful for control of motor movements and for dealing with fast moving situations.

One of the chief disadvantages of radio communication is that radio intelligence is one of the enemy's best methods of obtaining information of our plans, dispositions, and operations. In order to provide the necessary signal security a high state of training is required of all personnel. In North Africa the British have come to understand the importance of proper security measures in radio communication. In one campaign, security measures were poor and, as indicated below, valuable information fell into enemy hands. In a later campaign, corrective measures were taken; many of the earlier failings in the British signal security were remedied by the introduction of new procedure, combined with the reduction of traffic in the clear.

a. Lack of Signal Security

The following weaknesses in British signal security in one of the earlier campaigns resulted in the enemy acquiring valuable information on the strength and disposition of British forces and on their future plans.

(1) The enemy found it impossible to predict a certain attack from an examination of requests for supplies. The sudden increase in requests for rations, fuel, and ammunition indicated the imminence of an attack. It was this extra supply traffic, combined with the German knowledge of the code call system, which enabled the enemy to anticipate the attack, and to make the necessary dispositions to meet it.

(2) The exact location of British unit positions was made easier by one station asking another to call back at a prearranged time.

(3) The identification of units was often made much easier by the constant repetition of names and code references, and the almost complete lack of security measures in conversation under conditions of bad communication.

(4) Carelessness in the use of plain language, especially under battle conditions, allowed information to escape relating to matters as important as command and operation plans.

(5) The practice of giving the coordinates of enemy positions in the clear was of value to the Germans by giving them information as to:

(a) The exact location of their own troops.

(b) The general location of British troops, since the report of the position of enemy forces obtained by visual observation necessarily gives the approximate location of the reporting unit.

(c) British intentions. The traffic between two British stations included reporting in the clear locations of enemy tanks, followed by a reply stating an intention to attack then or at a prearranged time.

(6) From the number of captured British codes and documents found in enemy possession, it was evident that the practice of forwarding a code name or list to all units in a division, and of showing the complete distribution list, has proved of great value to the enemy in determining the exact British order of battle.

b. Success of Signal Security

The effects of improved methods were most clearly seen at the time of a later British offensive. The Germans were unaware as to whether British preparations were offensive or defensive, nor did they know either the time of the attack or the strength of the forces employed.

This lack of information was attributed to the new signal procedure, increased radio security measures, the observance of radio silence by units arriving in their assembly areas, and the fact that no special supply preparations were identified.