To support the D-day landings, 617 Squadron was given an unusual mission. It was tasked with pulling off a "spoof" raid. The squadron was to make a series of low level approaches to the Pas de Calais, dropping window with each pass. If delivered sequentially the window might simulate the approach of an invasion fleet and confuse the enemy about the real D-day landings in Normandy. 617 was disappointed, and felt they should be used in a more conventional manner to destroy real targets, but they did as they were told. In fact, they were the only unit that could pull it off. On the night of 5/6 June 1944, 617 Squadron used precision flying to drop window over the channel at low level in succession, generating the radar appearance of large numbers of approaching ships. This "spoof" raid simulated the approach for an amphibious landing in the Pas de Calais. In retrospect Cheshire felt they may have saved more lives with this mission than in any of the others they did.