The main daylight operations over the North Sea were now allocated to the Blenheims of 2 Group and operations were flown on 34 out of 47 days between 14 February and 1 April. Most of these flights were uneventful, though German ships were bombed on at least 6 occasions and the Blenheims several times encountered German fighters. A total of 250 Blenheim sorties were flown of which 9 were purely photo-reconnaissance flights to the German coast. 4 Blenheims (1 6 percent of those dispatched) were lost; all were believed to have been shot down by fighters. In addition to the Blenheim operations, 26 Wellington and 21 Hampden sorties were flown but these are all recorded as 'training sweeps' and no contact was made with any German forces and no casualties were suffered.
There was one confirmed bombing success for a Blenheim. On 11 March Squadron Leader M. V. Delap of 82 Squadron attacked a U-boat off Borkum bombing from such a low altitude that his aircraft was damaged by the explosions and nearly crashed. German records show that this was their Type VIIIA submarine U-31 and that Squadron Leader Delap's bombs sank it. This U-boat was later salvaged and repaired but was sunk by the British destroyer Antelope in the Atlantic on
