Many of the German radar stations on the French coast were destroyed by the RAF in preparation for the landings. On the night before the invasion, in Operation Taxable, 617 Squadron (the famous "Dambusters"), along with dropped strips of "window", metal foil that caused a radar return mistakenly interpreted by German radar operators as a naval convoy approaching Cap d'Antifer (about 80 km from the actual D-Day landings). The illusion was bolstered by a group of small vessels towing barrage balloons. No. 218 Squadron RAF also dropped "window" near Boulogne-sur-Mer in Operation Glimmer. On the same night, a small group of Special Air Service (SAS) operators deployed dummy paratroopers over Le Havre and Isigny. These dummies led the Germans to believe an additional airborne assault had occurred.