communicate with other ships and with shore stations.
At about the
same time, major military headquarters were provided radios to
improve communications and provide a quick method of interfacing with
national military commands.
EW closely followed the development of
used to identify ships and military units. As nations improved their
intelligence gathering systems, they also introduced methods to
and ciphers were developed, and the periodic changing of call signs
disrupting of communications (jamming) and the creation of deceptive
a. World War I.
During this period, EW was mostly limited to
casual monitoring of radio and some attempts at wiretapping.
radio direction finding was conducted; however, these early attempts
were very crude, and the results were unreliable.
The expanded use
of codes and ciphers for diplomatic cables continued with the
development of military radio use during and after World War I.
b. World War II.
The period between the two world wars saw
dramatic breakthroughs in the development of radio. The use of radio
in the military became commonplace. Radios were found as far down as
Signal operations became more disciplined.
and ciphers provided transmission security, and call signs and
frequencies were regularly changed.
By the start of World War II,
most nations had positions for EW functions within their staff
Jamming of radios became a component of EW, along with
collecting, locating, and analysis. Some major breakthroughs in code
breaking took place.
Several countries, including Great Britain,
Poland, the USSR, and the USA, were able to read the radio messages
of other nations.
(1) By the end of World War II, radios could be found at
concern, as the radio passed from the exclusive charge of the trained
signal soldier to the less security-conscious front-line soldier.
(2) The use of deception became an integral part of planning.
An interesting example of deception took place in England during the
time of the Allied invasion of France.
It was well known to the
Allies that the German high command felt the main invasion would be
at Calais. The Germans believed the landings in Normandy were only a
ruse to draw its forces away from Calais. To