'FY' was a British naval undertaking associated with the passage of the JW.58 outbound convoy to ports in the northern USSR (27 March/4 April 1944).

The JW.58 convoy comprised 44 merchant ships and the US light cruiser Milwaukee, which was being transferred to the USSR, departed Loch Ewe on 27 March. Under the overall command of Rear Admiral F. H. G. Dalrymple-Hamilton in the light anti-aircraft cruiser Diadem, the strong escort was centred on the escort carriers Activity and Tracker (as well as Diadem) within the convoy. The local escort between 27 and 29 March was provided by the corvettes Rhododendron and Stalwart, and minesweepers Onyx, Orestes and Rattlesnake. Close escort between 27 March and 4 April was entrusted to the destroyers Westcott, Whitehall and Wrestler, and corvettes Bluebell, Honeysuckle and Lotus.

The convoy was joined from Iceland by three more ships, of which one turned back with problems, together with the frigate Fitzroy and minesweepers Chamois and Chance. On 29 March the convoy was joined by its primary escort, which comprised the destroyers Impulsive, Inconstant, Obedient, Offa, Onslow, Opportune, Oribi, Orwell, Saumarez, Serapis, Scorpion, Venus and Free Norwegian Stord. These were complemented by the destroyers Beagle, Boadicea, Keppel and Walker, and by the sloops Starling, Magpie, Wild Goose, Wren and Whimbrel of Captain F. J. Walker�s 2^nd Support Group on loan from the Admiral Sir Max Horton�s Western Approaches Command to 4 April.

Providing distant support were the elements of Admiral Sir Bruce Fraser�s Home Fleet already at sea for �Tungsten� after departing Scapa Flow on 30 March: under the command of Vice Admiral Sir Henry Moore, second in command of the Home Fleet, these comprised the battleships Anson and Duke of York, fleet carriers Furious and Victorious, escort carriers Emperor, Fencer, Pursuer and Searcher, light cruisers Belfast, Jamaica and Sheffield, light anti-aircraft cruiser Royalist, and destroyers Milne, Meteor, Onslaught, Undaunted, Ursa, Verulam, Vigilant, Virago, Wakeful and Canadian Algonquin and Sioux.

Three days after the convoy�s departure, a reconnaissance flight by a German aeroplane located and reported the convoy, and there followed a succession of battles between the shadowers and the British carrierborne fighters. The latter did notably well, shooting down no fewer than six long-range aircraft during the convoy�s passage. As soon as the reconnaissance aircraft had located the convoy, the Germans moved the �Blitz� (iv), �Hammer� (iv) and �Thor� wolfpacks to a patrol line to the south-west of Bjørnøya with orders to attack on the last night of March, by which time 16 boats were in position.

The convoy escorts were more than a match for the U-boats, however, and it was Walker�s Starling which drew first blood when, on 29 March, she sank Oberleutnant Klaus Fischer�s U-961. Two days later the destroyer Beagle and aircraft from Tracker accounted for Korvettenkapitän Günter La Baume�s U-355. On 2 April Keppel sank Kapitänleutnant Klaus Becker�s U-360 with her Hedgehog anti-submarine mortar and, when a Fairey Swordfish anti-submarine aeroplane located Oberleutnant Willy Meyer�s U-288 very early on the next day and summoned a Grumman Wildcat fighter and Grumman Avenger anti-submarine aeroplane, between them the three aircraft destroyed the boat.

The escorts thus achieved a major success, and the new air organisation and tactics implemented in this operation had fully justified themselves. Apart from one ship, which was damaged by ice and had to return, the convoy arrived unscathed, being met off the coast by the Soviet destroyers Gremyaschiy, Kuybyshev, Razumnyi and Razyaryonnyi.

The Germans vastly over-claimed: the assessment of losses inflicted was nine destroyers sunk and four probably sunk. The Germans did admit, though, that the presence of strong air cover over and around the convoy had led to heavy U-boat losses, and as a result the Germans discontinued the practice of shadowing convoys by day.