'DV' was a British naval operation off the coast of neutral Norway to seize German fishing vessels and cover British ships laying mines off Norway early in April (31 March/8 April 1940).
The British ships involved were the light cruiser Birmingham and destroyer Fearless, joined later in the same day off Muckle Flugga by the destroyer Hostile, which had refuelled at Sullom Voe in the Shetland islands group.