Operation Flax: The Use of Signals Intelligence in the Destruction of the German Air Transport Fleet During the Tunisian Campaign, April 1943

During April 1943 Allied air forces in North Africa launched an air interdiction campaign, codenamed Operation FLAX, which inflicted heavy losses on the transport fleet of the Luftwaffe. The operation was facilitated by detailed Signals Intelligence (SIGINT) information provided by the British codebreaking centre at Bletchley Park. This SIGINT has usually been identified as the famous Ultra intelligence derived from the breaking of the German Enigma machine and other high-grade Axis cipher systems; however, material gathered from messages in low-grade (low security) Luftwaffe codes was of even greater importance. Exploitation of low-grade communications involved the use of innovative analytical techniques and machinery to turn thousands of pieces of tactical information received daily into actionable intelligence. Operation FLAX is a clear example of the operational impact of SIGINT in the Second World War, which highlights the use and usefulness of an often overlooked SIGINT source.