'FX' was a British naval undertaking associated with the passage of the JW.57 outbound and RA.57 homebound convoys to and from ports in the northern USSR (20 February/11 March 1944).

Up to this time it had been the British practice, in the hope of avoiding German detection, to despatch outward convoys in two smaller sections rather than one larger convoy, but Admiral Sir Bruce Fraser, commanding the Home Fleet, now decided to despatch large convoys with the strongest possible escort including, as Fraser had successfully negotiated with Admiral Sir Max Horton’s Western Approaches Command for the loan of additional resources, stronger support groups and more escort carriers.

On 20 February the JW.57 convoy departed Loch Ewe with 42 laden ships and, as the local escort to 22 February, the corvettes Burdock and Dianella, and the minesweepers Hydra, Loyalty, Orestes and Rattlesnake, which were replaced between 22 and 28 February by the close escort of the destroyers Beagle, Boadicea, Keppel and Walker, and the corvettes Bluebell, Camellia, Lotus and Rhododendron. On 22 February Vice Admiral I. G. Glennie’s ocean escort force arrived with the escort carrier Chaser, the light anti-aircraft cruiser Black Prince, the destroyers Wanderer and Watchman, and the frigates Byron and Strule.

Captain I. M. R. Campbell’s 3^rd Destroyer Flotilla (Milne, Mahratta, Matchless, Meteor, Obedient, Offa, Onslaught, Oribi, Savage, Serapis, Swift, Verulam and Vigilant) and a support group led by Commander I. G. Tyson on board the destroyer Keppel then joined the convoy’s escort.

Vice Admiral A. F. E. Palliser’s covering force comprised the heavy cruisers Berwick, Kent and Norfolk and the light cruiser Jamaica as well as a number of destroyers.

On 23 February a Junkers Ju 88 medium-range maritime reconnaissance bomber located the convoy, and then a Focke-Wulf Fw 200 Condor long-range maritime reconnaissance aeroplane maintained contact for more than 10 hours. The 'Werwolf' (i) wolfpack (U-312, U-313, U-362, U-425, U-601, U-674, U-713, U-739, U-956 and U-990) was deployed against the convoy, and the 'Hartmut' wolfpack (U-315, U-366, U-472 and U-673) was also despatched to the area.

On 24 February an Fw 200 maintained contact despite attacks by the Grumman Wildcat fighters launched by Chaser, and brought up U-425, U-601, U-713 and U-739, Oberleutnant Henri Gosejacob’s U-713 being depth-charged and sunk by Keppel on 24 February. By the evening of 25 February the U-boats had been driven off and a Consolidated Catalina flying boat of the RAF’s No. 210 Squadron, operating at the limit of its radius from Lerwick in the Shetland islands group, had sunk Oberleutnant Otto Hansen’s U-601. However, during the evening of the same day Kapitänleutnant Hubert Nordheimer’s U-990 torpedoed and sank the destroyer Mahratta, only two of whose crew were rescued by the destroyer Impulsive. Although Fw 200 and Ju 88 aircraft maintained contact on 26 and 27 February, only U-956, U-366 (four times), U-278, U-312 and U-362 were able to make attacks on the escort vessels, and none of these was successful.

On 28 February the convoy, now also escorted by the Soviet destroyers Gromkiy, Gremyashchiy, Razumnyi and Razyaryonnyi, four minesweepers and four submarine chasers, entered the comparative safety of the Kola inlet while still be shadowed by German reconnaissance aircraft. Seven transports and three tankers remained with the British minesweepers Gleaner and Seagull and the Soviet escorts to the White Sea.

The remaining U-boats (U-307, U-315, U-472 and U-739) were now grouped as the 'Boreas' wolfpack to operate against the westbound convoy which was now expected on the basis of earlier Allied practice. U-278, U-288, U-354, U-361, U-366, U-673, U-959 and U-973 then joined the first four boats, in some cases after a brief replenishment.

During the passage of the convoy, the British undertook the 'Bayleaf' operation in which the elderly fleet carrier Furious launched air attacks on the Norwegian coast during 24 February, the carrier being escorted by the battleships Anson and French Richelieu, two cruisers and seven destroyers belonging to the force. Of the last, Musketeer and the Free Polish Błyskawica were damaged in a collision.

On 2 March the RA.57 convoy departed with 31 unladen ships and the escort forces which had arrived with the JW.57 convoy, together with Tyson’s close escort (destroyers Keppel, Beagle, Boadicea and Walker, corvettes Bluebell, Camellia, Lotus and Rhododendron, and minesweepers Gleaner and Seagull). The ocean escort was strengthened by the escort carrier Chaser, the light anti-aircraft cruiser Black Prince and the destroyers Milne, Impulsive, Matchless, Meteor, Obedient, Offa, Onslaught, Oribi, Savage, Serapis, Swift, Verulam and Vigilant.

While Soviet destroyers, minesweepers and submarine chasers undertook sweeps in search of U-boats to the north of the Kola inlet, the convoy made a wide detour to the east but was nonetheless located by German air reconnaissance on 4 March. In the night U-739 just failed to torpedo the destroyer Swift. After missing with one torpedo, U-472 was damaged by an aeroplane of the FAA’s Nos. 816 Squadron from Chaser and then scuttled by its crew under fire from the approaching destroyer Onslaught.

On the following day Oberleutnant Joachim Brünner’s U-703 sank the 7,062-ton British Empire Tourist, and only just missed Milne. German reconnaissance aircraft maintained contact and made a series of sighting reports between 5 and 7 March, but on 5 and 6 March only U-278, U-288, U-673 and U-959 were able to make attacks, albeit unsuccessfully, on destroyers of the escort. Icing was a severe impediment to the effective use of the U-boats' anti-aircraft cannon, and as a result a Fairey Swordfish anti-submarine aeroplane of No. 816 Squadron from Chaser sank Oberleutnant Bruno Langenberg’s U-366 and Oberleutnant Klaus Paepenmöller’s U-973 on 5 and 6 March respectively.

The RA.57 convoy reached Loch Ewe on 10 March under the local escort of the minesweepers Hydra, Loyalty, Onyx, Orestes and Ready.