page_title: German Radio Intelligence Operations during World War II
section_title: Campaign in the West 1940
hierarchical_section_title: German Radio Intelligence Operations during World War II / Intercept operations during World War II / Campaign in the West 1940
context_page_description: German Radio Intelligence Operation were signals intelligence operations that were undertaken by German Axis forces in Europe during World War II. In keeping with German signals practice since 1942, the term communication intelligence had been used when intercept units were assigned to observe both enemy radio and wire communication. When the observation of only enemy radio communication was undertaken, the term was radio intelligence. The term intercept service was also used up until 1942.
context_section_description: Prior to the beginning of the Western Campaign on 10 May 1940, the operations and command channel structure of German radio intelligence was divided into four chronological phases. (See Chart 3, a-d Note: Chart a and b are before and after the campaign)
  Up to January 1940, the fixed intercept stations were under direct OKH jurisdiction with regard to long-range intelligence covering France, Belgium, the Netherlands and Great Britain. Following instructions from OKH, Intercept Evaluation Centre #3, operating from Army Group 3 HQ in Frankfurt am Main, which was then responsible for operations in the West, ordered the mobile intercept companies to intercept Belgium and French traffic emanating from the border region. The intercept companies which became available for reassignment at the end of the Polish campaign were sent to the west.
  For operations, the HQ of intercept troops with each army group was assigned one evaluation centre (NAAS) and two intercept companies; the fixed intercept station at Euskirchen had been temporarily motorized as an intercept company. The Münster and Stuttgart fixed intercept stations continued to co-operate with the commanders of intercept troops (the Münster station with Army Group B, and the Stuttgart station with Army Group C). It was intended to move them forward as soon as possible.
  Prior to the start of major operation the information obtained by radio intelligence from the northern sector held by the British and French forces was not particularly valuable because of the great distance involved, for instance 210 miles between Lille and Münster, and because of its largely technical character. Thus, all intercept units were thoroughly familiar with the French systems as a result of the many messages which had been copied. The intercept units of Army Group B were also familiar with the Belgium, Dutch and British systems. As early as December 1939, Germany decoded a special cryptographic system used by French command in radio messages to the armies and military district headquarters. It had been used, contrary to regulations, prior to the start of the war in September 1939. Germany was able to solve this system due to the radio station guilty of the violation, which was later reprimanded and thereupon repeated the same messages in the proper system. Their contents revealed a certain amount of organisational information, for example, the fact that the French 2nd Light Cavalry Division and 3rd Cavalry Division had been reorganised into the 1st Armoured Division and 2nd Armoured Division and were due to move into their assembly area northeast of Paris by 1 January 1940. However, this type of incomplete information could generally be considered only as a supplement to and confirmation of other intelligence concerning the Allies. It was not possible to deduce the Allies order of battle from radio intelligence alone.
caption: Chart 3-a. Operations by German Signal Intercept Units prior to Invasion of France and Low Countries August 1939 to October 1939