 The RN 's Operational Intelligence Centre selected the route and timing for the raid based on intelligence about the location of minefields and German recognition signals sourced from <unk> <unk> and knowledge of Luftwaffe patrols compiled by the Air Ministry 's Air Intelligence Branch . When all the plans had been pulled together and the timing worked out , the raid was expected to last no longer than two hours . The commandos and crew from Campbeltown would board the motor launches at the Old Mole jetty and then return to base . 
