This was the British first all-out air operation since October 1942 by Air Vice Marshal G. R. Bromet’s No. 19 Group of Air Marshal Sir John Slessor’s RAF Coastal Command against U-boats transiting the Bay of Biscay between their bases on the western coast of German-occupied France and their operational areas in the Atlantic (4/16 February 1943).
The operation saw the delivery of eight attacks in the course of 19 sightings (out of 41 boats known by the Allies to have crossed the Bay of Biscay), but only one U-boat was sunk. This second Bay of Biscay offensive involved nine Consolidated Liberator maritime patrol bombers of No. 224 Squadron, 16 Liberator machines of No. 86 Squadron (transferred to Iceland from March), six Consolidated Catalina maritime patrol flying boats of No. 210 Squadron, 16 Vickers Wellington medium-range patrol bombers of each of Nos 304 (Polish) and 311 (Czech) Squadrons, 16 Wellington machines of No. 172 Squadron, nine Handley Page Halifax long-range maritime patrol bombers of No. 58 Squadron, nine Boeing Fortress long-range maritime patrol bombers of No. 59 Squadron, 16 Armstrong Whitworth Whitley medium-range maritime patrol bombers of No. 502 Squadron, six Short Sunderland long-range patrol flying boats of each of Nos 10 and 461 Squadrons RAAF, and 12 B-24 Liberator machines (transferred from Morocco in March) of the USAAF’s Anti-Submarine Squadrons 1 and 2. In addition, from April, there were six Sunderland flying boats of No. 228 Squadron and 16 Wellington machines of No. 407 Squadron RCAF.
In ‘Gondola’ there were 312 sorties, 19 sightings and eight attacks in which, however, only limited damage was inflicted. In the first experimental deployment of a Wellington with ASV.Mk IV radar and a Leigh Light, Oberleutnant Ernst Heydemann’s U-268 was sunk on 19 February by an aeroplane of No. 172 Squadron. U-211, U-508 and U-525 were damaged on 20 February, 26 February and 3 March respectively, the last shooting down its Wellington attacker of No. 172 Squadron. U-519 was also sunk by a Liberator of the USAAF, but a major tactical reserve was that one boat had reported that it had been attacked by an aeroplane whose radar emissions had not been detected by the German Metox radar receiver. The Germans now knew that the Allies were fielding a new type of radar and set about discovering its features and therefore how to defeat it.