As more and more “secrets” about the D-Day invasion on the Normandy beaches come to light, there have been questions about what the German high command were seeing, knew and thought they knew. There were a number of mis-information campaigns running prior to D-Day, some of which are recounted on this forum. One such operation was the “invasion” on the night of 5/6th June targeted at an area well north of the actual landing beaches and towards the Pas-de-Calais. It was carried out by 617 Squadron at low level and with extreme precision in flying speed and navigation and using an innovative design by Joan Curran (nee Srothers), a Swansea girl who while working at the Telecommunications Research Establishment at Swanage developed a system of thin aluminium foil strips for disrupting radar which became known as “Window”; these days it’s known as “chaffe”. The “invasion” required a small number of Lancasters flying forward for a set distance (timed by stopwatch), dropping bundles of “Window”, turning 180 degrees at a set rate and backtracking for another timed leg before turning again to repeat the whole procedure. The idea was that the Germans would see a radar plot of a large slow moving radar response or target heading across the Dover Straits and towards the Pas-de-Calais. The timings of all the turns by the aircraft, their tracks, the horizontal spacing between them and all the other actions including being relieved by other aircraft from the squadron had been carefully calculated to give the German radar operators the impression of a large naval assault force heading their way. The success of the “phantom invasion” became apparent when after watching the approach of this invasion force on their radar screens all night, dawn broke, they looked out over the straits and there it was … gone! By the time they realised that they’d been had and the real invasion was happening in Normandy, it was too late.