Training was forgotten on May 16th, when a party was held in the officers mess, to celebrate the first anniversary of the ‘Dams Raid’. All former members of the squadron who had taken part were invited, though Guy Gibson was not able to attend. However many others did, including several representatives from A V Roe and Vickers who had worked on the original project.Three days later a dance was held for all ranks and this time Gibson was there, he received a rousing reception as he entered the room. Gibson and Cheshire were presented with a cake in the shape of a dam. Responding to cries of "speech, speech" Gibson climbed onto a table, to wild applause and promptly stood in the cake, he immediately remarked on the dangers of 'icing' ( a common hazard for aircrews at altitude) which just added to the uproar. On the night of the 5th / 6th June, No 617 Sq took to the skies in sixteen Lancasters, in two groups of eight, separated by an hour. They were to fly Operation Taxable in conjunction with Operation Glimmer which would be flown by aircraft of No 218 squadron. Each aircraft was fitted with extra flare chutes and carried crews of between 11 and 14 including an extra pilot and navigator. Each aircraft would fly a straight course towards the Pas–de–Calaise for two and a half minutes at 3,000 ft and a speed of 180mph, dropping bundles of 'window' every 15 seconds. With the aircraft 2 miles apart they would create a wall of 'window' 16 miles wide. On a given signal they would turn 180 degrees and fly back for two minutes ten seconds still dropping 'window', before turning again for France and repeating the procedure. By reducing the amount of time spent heading back to the English coast, the Lancasters gave German radar the impression of a huge armada crossing the channel at 8 knots. By dropping larger strips of 'window' on the approach leg, and smaller strips on the return leg the illusion was enhanced. After an hour, the first group continued back to the British coast on their return leg and the second wave took over on the outward leg, for the next hour. Despite this not being a bombing or marking operation, for the crews it was one of the most precise and concentrated missions of the whole war, any deviation would have given the game away. In the event, Operation Taxable was an overwhelming success, with large numbers of German units drawn away from Normandy. As French resistance units reported these movements, aircraft from the 2nd Tactical Airforce attacked bridges along the route of march, preventing their return to Normandy,German coastal batteries were also reported shelling an empty channel. Meanwhile, Operation Overlord was underway.... Even as 617 Squadron was preparing to depart on Operation Taxable, large tarpaulin covered trailers began arriving at the bomb dump, Barnes Wallis had a new toy for No 617 Squadron.....