There were many deceptions leading up to D-Day but I thought this one was particularly clever. The allies had aircraft fly tight and pre-determined formations out in the channel. They did this at a specific speed and level and dropped chaff whilst doing so. Apparently the radar reflections caused by this fooled the Germans into thinking a fleet of ships was heading for Boulogne. The more I learn about all these clever WW2 tricks, the more impressed (and grateful) I am to the men and women who played their parts in this conflict The National Archives Learning Curve | World War II | Western Europe 1939-1945: D-Day | Why was D-Day successful?