'Hartmut' (ii) was the U-boat wolfpack operation in the in the Norwegian Sea against the 'FX'-supported passage of the JW.57 convoy (23/28 February 1944).

The wolfpack comprised U-315, U-366, U-472 and U-673, and neither lost any of its own number nor sank any ship.

On 20 February the JW.57 convoy departed Loch Ewe on the western coast of Scotland with 42 laden ships and a local escort comprising the corvettes Burdock and Dianella, and the minesweepers Hydra, Loyalty, Orestes and Rattlesnake. On 22 February this local escort was replaced, for the period up to 28 February, by a close escort comprising the destroyers Beagle, Boadicea, Keppel and Walker, and the corvettes Bluebell, Camellia, Lotus and Rhododendron.

On 22 February there arrived Vice Admiral I. G. Glennie’s ocean escort, comprising the escort carrier Chaser, the light anti-aircraft cruiser Black Prince, the destroyers Wanderer and Watchman, and the frigates Byron and Strule; a destroyer group with Milne, Mahratta, Matchless, Meteor, Obedient, Offa, Onslaught, Oribi, Savage, Serapis, Swift, Verulam and Vigilant; and Commander I. J. Tyson’s support group based on the destroyer Keppel.

Vice Admiral A. F. E. Palliser’s 1^st Cruiser Squadron (the heavy cruisers Berwick, Kent and Norfolk, and the light cruiser Jamaica) provided more distant cover.

The convoy was located on 23 February by a Junkers Ju 88 aeroplane of Oberst Hermann Busch’s Fliegerführer 'Nord' (West) command, and for more than 10 hours a Focke-Wulf Fw 200 Condor long-range maritime reconnaissance aeroplane shadowed the convoy and reported its changing position.

The 'Werwolf' wolfpack (U-312, U-313, U-362, U-425, U-601, U-674, U-713, U-739, U-956 and U-990) was deployed, and the 'Hartmut' (ii) wolfpack (U-315, U-366, U-472 and U-673) was despatched to bolster the German interception force.

On 24 February an Fw 200 maintained contact despite the efforts of Grumman Wildcat fighters launched from Chaser, and the information it radioed allowed U-425, U-601, U-713 and U-739 to be vectored into the area. However, Oberleutnant Henri Gosejacob’s U-713 was 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 had sunk Oberleutnant Otto Hansen’s U-601. But during the evening of the same day Kapitänleutnant Hubert Nordheimer’s U-990 torpedoed and sank the destroyer Mahratta, only two of her crew being rescued by the destroyer Impulsive.

Although Fw 200 and Ju 88 aircraft continued to shadow the convoy on 26 and 27 February, only U-956, U-366 (four times), U-278, U-312 and U-362 were able to make torpedo attacks on the escort vessels, and none of these attacks was successful.

On 28 February the convoy, whose escort had now been supplemented by the Soviet destroyers Gromkiy, Gremyashchiy, Razumnyi and Razyarennyi, four minesweepers and four submarine chasers, reached the Kola inlet while still being watched by German reconnaissance aircraft. Seven transports and three escorts continued with the British minesweepers Gleaner and Seagull and the Soviet escorts to the White Sea.

The boats remaining in the area (U-307, U-315, U-472 and U-739) were then formed into the 'Boreas' wolfpack to attack against the westbound convoy that was now expected. The 'Boreas' wolfpack was soon supplemented by U-278, U-288, U-354, U-361, U-366, U-673, U-973 and U-959 after some of these had been replenished.

On 2 March the RA.57 convoy departed with 31 unladen ships and the naval force which had escorted JW.57. The close escort comprised the destroyers Keppel, Beagle, Boadicea and Walker, the corvettes Bluebell, Camellia, Lotus and Rhododendron, and the minesweepers Gleaner and Seagull. The ocean escort was strengthened with 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 took the offensive against U-boats in the area to the north of the Kola inlet, the convoy undertook a wide detour to the east but was nonetheless located by German air reconnaissance on 4 March. In the night U-739 just missed the destroyer Swift; Oberleutnant Wolfgang Friedrich Freiherr von Forstner’s U-472 also missed its target and was then damaged by an aeroplane of the FAA’s No. 816 Squadron from Chaser and scuttled by her crew under fire from the 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.

Continued German air reconnaissance shadowed and reported the convoy on 5, 6 and 7 March, but during 5 and 6 March only U-278, U-288, U-673 and U-959 were able to attack the escorts, albeit unsuccessfully. Icing greatly impeded the U-boats' ability to employ their anti-aircraft cannon, and as a result two Fairey Swordfish anti-submarine aircraft of the FAA’s No. 816 Squadron sank Oberleutnant Bruno Langenberg’s U-366 and Oberleutnant Klaus Paepenmöller’s U-973 on 5 and 6 March despite of difficult weather.

The convoy reached Loch Ewe safely on 10 March.