This was a British air attack on the German battleship Tirpitz and other warships in the Trondheimfjord of German-occupied Norway (27/28 April 1942).
The raid was undertaken by 12 Avro Lancaster and 31 Handley Page Halifax heavy bombers. The British bombers located their targets and attacked, but scored no hits and suffered the loss of one Lancaster and four Halifax aircraft.
The attack had originally been scheduled for 25/26 April, and to support this the escort destroyers Belvoir, Penn amd Hursley were detailed as rescue ships. After the raid’s postponement, Belvoir was ordered to proceed to Sullom Voe in the Shetland islands group, Penn was recalled to Scapa Flow in the Orkney islands group, and Hursley had not yet sailed.