Photo: Sir Martin’s map: Allied deception plans and Actual Allied operations
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…messages decrypted at Bletchley … revealed to the British planners of the Normandy landings that, for the Germans, the First United States Army Group was a reality. The phantom army group could therefore continue “threatening” Calais.
Not only was a fictitious United States Army Group to participate in these operations, but also an equally fictitious British Twelfth Army, containing, among its forces, the 15th British Motorized Division, the 34th British Infantry Division, the 8th British Armored Division, and the 7th Polish Infantry Division, all apparently equipped, deployed, moved, trained, and communicated with, and yet existing only on paper.
A separate deception army was set up in Scotland, intended to give verisimilitude to an Allied amphibious landing on the coast of Norway. German Intelligence worked hard to identify as many of its units as possible, and it succeeded in locating, among entirely fictional units, the First Norwegian Army, the 12th Norwegian Infantry Brigade, the 2nd Polish Infantry Division, the Polish Parachute Brigade, two American Infantry Divisions, and a British Army Corps
By reading Germany’s own top-secret messages that the Combined Chiefs of Staff would know whether the Germans had been taken in by Fortitude and by the other deceptions that were intended to ensure the widest possible dispersion of German forces by a skillfully leaked set of eight separate British landings. Each of these landings was a figment of the imagination, and deception skills, of the London Controlling Section under Colonel Bevan. As well as Fortitude South, pointing to the Pas-de-Calais as the cross-Channel destination, there was Fortitude North against central Norway, centered on Trondheim; Operation Graffham, against central Sweden; Operation Royal Flush, against the coastlines of three neutral countries: Sweden, Spain, or Turkey; Operation Zeppelin, a triple assault against the Romanian Black Sea coast, Crete, and the western coastline of Greece and Albania; Operation Ironside against Bordeaux; Operation Vendetta, against Marseille; and Operation Ferdinand against Rome.
A careful scrutiny at Bletchley of the Ultra decrypts revealed just how seriously the Germans were taking these nonexistent threats. Reports had been received, Churchill told General Sir Maitland Wilson, Commander-in-Chief of the British forces in the Mediterranean, “that the islands off the Dalmatian coast are being equipped with naval guns.” Churchill’s telegram was dated February 13; Ultra was his source.
Excerpt from D-Day
