Double-Cross System - V-weapons Deception

V-weapons Deception

The British noticed that, during the V-1 flying bomb attacks of 1944, the weapons were falling 2–3 miles short of Trafalgar Square — the actual Luftwaffe aiming points such as Tower Bridge were unknown to the British. Duncan Sandys was told to get MI5-controlled German agents such as Zig Zag and TATE to report the V-1 impacts back to Germany. In order to make the Germans aim short, the British used the double agents to exaggerate the number of V-1s falling in the north and west of London and not to report, when possible, those in the south and east. For example, circa June 22, 1944, only one of seven impacts was reported as being south of the Thames, when ¾ of the impacts had been there. Although Germany was able to plot a sample of V-1s which had radio transmitters, which confirmed that they had fallen short, the telemetry was disregarded in favour of the human intelligence.

When the German 65th Army Corps received a false Double Cross V-1 report that there was considerable damage in Southampton —which had not been a V-1 target—the V-1s were temporarily aimed at the South Coast Ports. V-1s were extremely powerful. As a result, the Double Cross deception also caused retargetting from London, not just inaccurate aiming. However, when V-1s launched from Heinkel He 111s at Southampton on July 7 were inaccurate, British advisor Frederick Lindemann recommended the agents report that the attack caused "heavy losses" in order to save hundreds of Londoners each week at the expense of only a few lives in the ports. When the Cabinet learned on August 15 of the deception, Herbert Morrison said that they had no right to decide that one man should die while another should survive, but the deception was approved to continue.

Moreover, when the subsequent V-2 rocket blitz began with only a few minutes from launch to impact, the deception was enhanced by providing locations genuinely damaged by bombing, verifiable by aerial reconnaissance, for impacts in central London, but each time-tagged with the time of an earlier impact that had fallen 5–8 miles short of central London. From mid-January to mid-February 1945, the mean point of V-2 impacts edged eastward at the rate of a couple of miles a week, with more and more V-2s falling short of central London.