On 12 December, 8 Whitleys commenced this new type of operation to harass the German seaplanes which were laying mines off the English coast. Flying in relays, Whitleys flew during the evenings over suspected seaplane bases on the islands of Sylt, Norderney and Borkum. If flare-paths on the water were seen to be lit, bombs were dropped but only in the water because of the instructions given to bomber units, after President Roosevelt's bombing-restraint appeal at the outbreak of war, that no bombs should be dropped on any land targets.
These operations were flown on 17 nights between the evening of
