could tell Horton, who was attempting to direct ONS.5 from his office at Derby House, was that the three U-boat groups were ‘in the general area off Newfoundland’.11 This blindness meant that nobody in the Royal Navy, least of all Gretton, knew that on 27th April, sixteen new U-boats had been instructed by BdU to assemble into a fourth wolfpack, Gruppe Star (Starling), east of Greenland, directly across the convoy’s path.
