This was a U-boat wolfpack operation off the north-west coast of German-occupied Norway against the RA.59 convoy (20 April/3 May 1944).
The ‘Donner’ wolfpack comprised U-277, U-307, U-312, U-315, U-354, U-362, U-636 and U-703, while the ‘Keil’ wolfpack comprised U-278, U-313, U-361, U-387, U-674, U-711 and U-739, and for the loss of Kapitänleutnant Robert Lübsen’s U-277, Oberleutnant Harald Muhs’s U-674 and Oberleutnant Friedrich Weitz’s U-959 sank only one 7,176-ton ship.
On 21 April Rear Admiral R. R. McGrigor’s British escort force 1 steamed to the Kola inlet to support the RA.59 convoy and at the same time to bring back the 1,366-man crew of the US light cruiser Milwaukee after her transfer to the Soviet Northern Fleet. It had also been planned that the 19,991-ton liner Nea Hellas would also collect 1,430 Soviet sailors for vessels to be taken over in the UK, but this part of the undertaking was cancelled.
On 21 April Vice Admiral Sir Henry Moore, second in command of Admiral Sir Bruce Fraser’s Home Fleet, had meanwhile put to sea with the battleship Anson, fleet carriers Furious and Victorious, escort carriers Emperor, Pursuer, Searcher and Striker, and a number of cruisers and destroyers to steam to the coast of German-occupied northern Norwegian coast to carry out a carrierborne air attack on the German battleship Tirpitz and, at the same time, shield the convoy operation.
Farther to the east, after the BK.12 feeder convoy of 17 ships from the White Sea, led by the icebreakers Iosif Stalin and Lenin and accompanied by the Soviet destroyers Gremyashchiy, Gromkiy, Groznyi, Razumnyi and Kuybyshev as well as a minesweeper and five patrol ships, had reached the Kola inlet on 27 April, the RA.59 convoy departed on the following day with the escort force and, initially, the Soviet destroyers Gremyashchiy and Razyaryonnyi, three minesweepers and six submarine chasers. The US crew of what was now the Soviet cruiser Murmansk was spread among the ships, as were 2,940 Soviet sailors to man the British units (one battleship, nine destroyers and four submarines) earmarked for transfer as the Soviet share of the Italian war booty now in the UK.
The ocean escort from 28 April to 3 May comprised the escort carrier Fencer, light anti-aircraft cruiser Diadem, and destroyers Boadicea, Ulysses, Verulam, Virago, Walker and Whitehall, from 28 April to 4 May the escort carrier Activity and destroyers Milne, Marne, Matchless, Meteor and Musketeer, and from 8 April to 6 May the destroyers Keppel, Beagle, Inconstant, Westcott and Wrestler, corvette Lotus and Canadian frigates Cape Breton, Grou, Outremont and Waskesiu.
The convoy was located and reported by German air reconnaissance toward 24.00 on the night of 28/29 April, and the ‘Donner’ and ‘Keil’ wolfpacks, which were waiting for an eastbound convoy, were deployed against the RA.59 convoy from 30 April. After U-307 missed the convoy with a torpedo salvo, U-387 and U-711 made several attacks on the destroyers and ships toward 24.00 on the night of 30/31 April, U-711 sinking the 7,176-ton US William S. Thayer. During 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 U-277 on 1 May and two Swordfish aircraft of the FAA’s No. 842 Squadron sank U-959 and U-674 on 2 May, while U-307 and U-711 again missed the destroyers. Early on 3 May U-278 was attacked by two Swordfish and one Grumman Wildcat aircraft, but shot down the last and escaped.