2025/06/17 by Stephen G Coulson · 2 voices
Engineering · Social Sciences · #Intelligence, Security, War Strategy #Military Defense Systems Analysis #Military Strategy and Technology
paper · pdf · doi:10.1080/08850607.2025.2504000
openalex publication_date 2025/06/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/14
In November 1939, the British Expeditionary Force (BEF) received warning of a German invasion of Belgium and Holland that originated from Col. Hans Oster, the Abwehr’s deputy chief of counterintelligence. This warning is usually attributed as being passed to the BEF via the Dutch military attaché in Berlin, Maj. G.J. Sas; however, analysis of the records of the intelligence staffs shows that it was actually a warning Oster sent to a contact of his in Rome that was the first report to reach the BEF. The greatest intelligence gap for the BEF was the exact timing of the German invasion; the Oster reporting provided the only timely, unambiguous warning. Without this, it is unlikely that there would have been sufficient indicators for Allied intelligence to predict the time of the invasion from other available sources. This historical case study highlights the importance of military attachés as a source of intelligence, as well as revealing some of their limitations and the difficulties of using their networks of casual contacts. The different reactions to the Oster–Sas reporting by the senior BEF commanders show how personality, experience, and military situation all greatly affected their use of intelligence.