'Keil' was a U-boat wolfpack operation in the Norwegian Sea against the RA.58 and RA.59 convoys (5/20 April and 28 April/6 May 1944).
The wolfpack comprised U-315, U-361, U-711, U-716 and U-739, and for the loss of none of its own number sank only one craft, a 10-ton motor fishing vessel.
The RA.58 convoy of 38 unladen ships departed the Kola inlet for Loch Ewe on 7 April. The ocean escort between 7 and 12 April comprised the escort carrier Activity and destroyers Keppel, Beagle, Boadicea, Inconstant, Venus, Walker, Westcott, Whitehall and Wrestler with, between 7 and 13 April, the light anti-aircraft cruiser Diadem and destroyers Onslow, Offa, Opportune, Orwell, Saumarez, Serapis and Free Norwegian Stord, and between 7 and 14 April the escort carrier Tracker, destroyers Impulsive, Obedient, Oribi and Scorpion, and corvettes Bluebell and Honeysuckle as well as Captain F. J. Walker’s 2nd Support Group (sloops Starling, Magpie, Whimbrel, Wild Goose and Wren).
Because of the heavy losses it had sustained in operations against the JW.58 convoy, the Luftwaffe could fly only night radar reconnaissance flights, which did not discover the convoy until 9 April.
Of the U-boats formed in the 'Donner' and 'Keil' wolfpacks (U-277, U-313, U-347, U-361, U-362, U-636, U-703, U-711, U-716 and U-990), only U-361, U-362 (twice), U-703 and U-313 managed to reach the position from which they could fire torpedoes against the destroyers on 10 April, although without success.
The RA.58 convoy was once more located by air reconnaissance early on 11 April, but the German operation had to be terminated as the convoy was now too far ahead of the boats to be caught and attacked.
On 21 April an escort force commanded by Rear Admiral R. R. McGrigor and comprising the light anti-aircraft cruiser Diadem, escort carriers Activity and Fencer, destroyers Milne, Meteor, Marne, Matchless, Musketeer, Verulam, Ulysses and Virago (3rd Destroyer Flotilla), Canadian frigates Waskesiu, Grou, Cape Breton and Outremont (6th Support Group) and destroyers Keppel, Walker, Beagle, Westcott, Whitehall, Wrestler, Inconstant, and Boadicea and corvette Lotus (8th Support Group) departed British waters for the Kola inlet to escort the RA.59 convoy of 45 unladen ships and to bring back the 1,366-man crew of the US light cruiser Milwaukee just transferred to the Soviet navy. The planned participation of the liner Nea Hellas to take 1,430 Soviet sailors for vessels to be taken over in the UK was cancelled.
The escort forces reached the Kola inlet on 23 April. After the BK.12 feeder convoy of 17 unladen ships from the White Sea, led by the icebreakers Iosif Stalin and Lenin and accompanied by the Soviet destroyers Gremyashchy, Gromky, Grozny, Razumny and Kuybyshev, minesweeper T-119 and five patrol ships, had reached the Kola inlet on 27 April, the RA.59 convoy sailed on the following day with its escort, which was at first reinforced by the Soviet destroyers Gremyashchiy and Razyaronnyi, minesweepers T-112, T-114 and T-119, and six submarine chasers. The US sailors of the Milwaukee's crew were distributed among the ships, as too were 2,940 Soviet sailors to man the British units (one battleship, nine destroyers and four submarines) which were to be taken over as part of the Soviet share of the Italian war booty currently located in the UK.
The ocean escort between 28 April and 3 May comprised the light anti-aircraft cruiser Diadem, escort carrier Fencer and destroyers Boadicea, Ulysses, Verulam, Virago, Walker and Whitehall, and between 28 April and 4 May the escort carrier Activity and destroyers Milne, Marne, Matchless, Meteor and Musketeer. The close escort comprised the destroyers Keppel, Beagle, Inconstant, Westcott and Wrestler, Canadian frigates Cape Breton, Grou, Outremont and Waskesiu, and corvette Lotus.
German air reconnaissance spotted and reported the convoy at about 24.00 on 28/29 April. The U-boats, which were lurking in wait for an eastbound convoy, were then redeployed against the RA.59 convoy from 30 April as the 'Donner' wolfpack (U-277, U-278, U-307, U-387 and U-636) and 'Keil' wolfpack (U-313, U-315, U-354, U-674, U-711, U-739 and U-959).
U-307 fired a torpedo salvo that missed the convoy, U-387 and U-711 made several attacks on the destroyers and merchant ships at about midnight on 30 April. Oberleutnant Friedrich-Georg Harrie’s U-307 sank the 7,176-ton US William S. Thayer. In the course of 1 May U-278, U-307 and U-959 each missed destroyers twice. A Fairey Swordfish anti-submarine aeroplane of the FAA’s No. 842 Squadron from Fencer sank Kapitänleutnant Robert Lübsen’s U-277 on 1 May, and two Swordfish aircraft of the same unit sank Oberleutnant Friedrich Weitz’s U-959 and Oberleutnant Harald Muhs’s U-674 on 2 May, while U-307 and U-711 again missed destroyers.
Early on 3 May U-278 was attacked by two Swordfish and one Grumman Wildcat aircraft, but shot down the last and managed to escape.